University of Belgrade Faculty of Technology and Metallurgy Department of Analytical Chemistry and Quality Control THE DEVELOPMENT AND APPLICATION OF HYBRID SORBENTS FOR DETERMINATION AND SELECTIVE REMOVAL OF ARSENIC(III) AND ARSENIC(V) FROM WATER Mr NUREDDIN A.A. BEN ISSA, chemist BELGRADE 2012 Univerzitet u Beogradu Tehnološko-metalurški fakultet Katedra za analitičku hemiju i kontrolu kvaliteta RAZVOJ I PRIMENA HIBRIDNIH SORBENATA ZA ODREĐIVANJE I SELEKTIVNO UKLANJANJE ARSENA(III) i ARSENA(V) IZ VODE Mr NUREDDIN A. A. BEN ISSA, dipl. hemičar BEOGRAD 2012 University of Belgrade Faculty of Technology and Metallurgy Department of Analytical Chemistry and Quality Control Thesis Committee _______________________________________ Dr Ljubinka Rajaković, professor of TMF, Thesis Supervisor ________________________________________ Dr Slavica Stevanović, professor of TMF ________________________________________ Dr Mirjana Ristić, professor of TMF ________________________________________ Dr Aleksandra Perić-Grujić, professor of TMF ________________________________________ Dr Antonije Onjia, scientific adviser of INN Vinča Candidate Mr Nureddin Ben Issa ___________________________________________ Date of thesis defence: 03.12.2012. University of Belgrade Acknowledgements First of all, I would like to thank my supervisor, Prof. dr Ljubinka Rajakovic, for her guidance, patience and enthusiasm concerning this thesis. Without her support, thesis would not have been finished. Then I would like to thank all of the professors and staff at the department of Analytical chemistry. I would like to thank everybody working at the TMF for welcoming me and helping me with the different problems that occurred during my stay. I also want to thank all of my friends who were supporting me. At last, but not the least, I would like to thank my family. A special thanks to my wife for her support for all of my endeavors. THE DEVELOPMENT AND APPLICATION OF HYBRID SORBENTS FOR DETERMINATION AND SELECTIVE REMOVAL OF ARSENIC(III) AND ARSENIC(V) FROM WATER ABSTRACT The aim of the thesis was the development and application of hybrid sorbents for determination of arsenic species in water and selective removal of arsenic from water. Water soluble arsenic species in natural water are inorganic (iAs) species, as arsenite, As(III) and arsenate, As(V). It is important to note that in neutral conditions, As(V) species are completely in ionic forms (H2AsO4- and HAsO42-), while As(III) is in molecular form (H3AsO3 or HAsO2). This fact was the base for the application of anion exchange resin and selective hybrid resins for the separation, determenation and removal of iAs. As a result of anthropogenic pollution in water can be present organic (oAs) species as monomethylarsenic acid, MMAs(V) and dimethylarsenic acid, DMAs(V). Methods developed for iAs species should consider oAs species as interferences for the iAs determinations. In the frame of these tasks, efficiency of three types of resins were investigated: a strong base anion exchange (SBAE) resin and two hybrid (HY) resins, HY-Fe which integrates sorption activity of hydrated iron oxides (HFO) with the anion exchange function and HY-AgCl which integrates effects of chemical reaction with the anion exchange function. Two systems were employed: a batch and a fixed bed flow system. The selective bonding of arsenic species on three types of resins makes possible the development of the procedure for measuring and calculation of all arsenic species in water. In order to determine capacity of resins, the preliminary investigations were performed in batch system and fixed bed flow system. Resin capacities were calculated according to breakthrough points in a fixed bed flow system which is the first step in designing of solid phase extraction (SPE) module for arsenic speciation separation and determination. The investigations performed in the scope were focused on: I) separation of As(III) and As(V) species (in order to determine both arsenic species which are prevailing in natural waters), II) separation of organic arsenic species (in order to determine of DMAs(V) and MMAs(V) in natural waters) and III) collection, preconcentration and removal of all arsenic species. The main achievement of thesis is that three methods for arsenic species determination were developed. First method is a simple method for the separation and determination of iAs species in natural and drinking water which was the main task of the thesis. Procedures for sample preparation, separation of As(III) and As(V) species and preconcentration of the total iAs on fixed bed columns were defined. Two resins: SBAE and HY-Fe were utilized. The governing factors for the ion exchange/sorption of arsenic on resins in a batch and a fixed bed flow system were analyzed and compared. Acidity of the water, which plays an important role in the control of the ionic or molecular forms of arsenic species, was beneficial for the separation; by adjusting the pH values to less than 8.0, the SBAE resin separated As(V) from As(III) in water by retaining As(V) and allowing As(III) to pass through. The sorption activity of the hydrated iron oxides (HFO) particles integrated into the HY-Fe resin was beneficial for bonding of all iAs species over a wide range of pH values from 5.0 to 11.0. The resin capacities in flow system were calculated according to the breakthrough points and pH value of water 7.5. The SBAE resin bound 370 µg/g of As(V) while the HY-Fe resin bound 4150 µg/g of As(III) and 3500 µg/g of As(V). The high capacities and selectivity of the resins were considered as advantageous for the development and application of two procedures, one for the separation and determination of As(III) (with SBAE) and the other for the preconcentration and determination of the total arsenic (with HY-Fe resin). The analytical properties of first method developed for the separation and determination of iAs: the limit of detection, LOD, was 0.24 µg/L, the limit of quantification, LOQ, was 0.80 µg/L and the relative standard deviations, RSD %, for samples with a content of arsenic from 10.0 to 300.0 µg/L ranged from 1.1 to 5.8 %. Second method is a simple and efficient method for separation and determination of inorganic arsenic (iAs) and organic arsenic (oAs) in drinking, natural and wastewater. Three types of resins were used: SBAE, HY-Fe and HY-AgCl were investigated. The quantitative separation of molecular and ionic forms of iAs and oAs was achieved by SBAE and pH adjustment, the molecular form of As(III) that exists in the water at pH < 8.0 was not bonded with SBAE, which was convenient for direct determination of As(III) concentration in the effluent. The HY-Fe resin was convenient for the separation of DMAs(V) from all other arsenic species, which were retained on the HY-Fe resin that has a high sorption capacity for the arsenic species, 9000 µg/g. Efficiency of HY-Fe resin makes possible direct measurements of this specie in the effluent. HY-AgCl resin retained all iAs which was convenient for direct determination of oAs species concentration in the effluent, the relative standard deviation (RSD) was between 1.3-5.6 %. The third method is a simple and efficient method for separation and determination of dimethylarsenate DMAs(V). Two resins, SBAE and HY-Fe were tested. By simple adjusting pH value of water at 7.0, DMAs(V) passed through the HY-Fe column without any changes, while all other arsenic species (inorganic arsenic and monomethylarsenate, MMAs(V)) were quantitatively bonded on HY-Fe resin. The resin capacity was calculated according to the breakthrough points in a fixed bed flow system. At pH 7.0, the HY-Fe resins bonded more than 4150 µg/g of As(III), 3500 µg/g of As(V) and 1500 µg/g of MMAs(V). Arsenic adsorption behavior in the presence of impurities showed tolerance with the respect to potential interference of anions commonly found in natural water. DMAs(V) was determined in the effluent by inductively coupled plasma mass spectrometry (ICP-MS). The detection limit was 0.03 µg/L and relative standard deviation (RSD) was between 1.1-7.5 %. For the determination of arsenic in all arsenic species in water two analytical methods were applied: the inductively coupled plasma mass spectrometry (ICP-MS) and hydride generation- atomic absorption spectroscopy (GH-AAS). Methods were established through basic analytical procedures (with external standards, certified reference materials and the standard addition method) and by the parallel analysis of some samples using the HG-AAS technique. Verification with certified reference materials proved that the experimental concentrations found for model solutions and real samples were in agreement with the certified values. ICP- MS detection limit was 0.2 µg/L and relative standard deviation (RSD) of all arsenic species investigated was between 3.5-5.1 %. The interference effects of anions commonly found in water were found to be negligible. Both methods could be applied routinely for monitoring arsenic levels in various water samples (drinking water, ground water and wastewater). Keywords: Arsenic; Speciation; Separation; Determination; Preconcentration; Ion exchange; Hybrid resin; Ion exchange resin, ICP-MS Scientific field: Chemistry Specific scientific field: Analytical chemistry RAZVOJ I PRIMENA HIBRIDNIH SORBENATA ZA ODREĐIVANJE I SELEKTIVNO UKLANJANJE ARSENA(III) I ARSENA(V) IZ VODE I Z V O D Cilj izrade ove teze je razvoj i primena hibridnih smola kao sorbenata za određivanje i selektivno uklanjanje arsenovih vrsta u vodi. Arsenove vrste rastvorne i prisutne u prirodnoj vodi su neorganska jedinjenja arsena (iAs), arseniti As(III) i arsenati As(V). Bitno je naglasiti da se u neutralnim uslovima, As(V) nalazi u jonskom obliku (H2AsO4- and HAsO42-), dok se As(III) nalazi u molekularnom obliku (H3AsO3 or HAsO2). Ova činjenica je osnova za primenu anjonskih, jonoizmenjivačkih smola i selektivnih hibridnih smola za razdvajanje i uklanjanje iAs. Kao rezultat antropogenog zagađivanja u vodi mogu da budu prisutne i vrste organskog arsena (oAs) kao što je monometilarsenova, MMAs(V) i dimetilarsenova kiselina, DMAs(V). Svaka metoda koja je razvijena za određivanje iAs mora da razmatra i reši problem prisustva oAs kao smetnji za određivanje iAs vrsta. U okviru postavljenih zadataka ispitana je efikasnost tri tipa smola: jako bazna anjonska smola (SBAE) i dve hibridne (HY), HY-Fe koja integriše sorpcionu aktivnost hidratisanog gvožđe oksida (HFO) sa anjonsko-izmenjivačkom funkcijom i HY-AgCl koja integriše efekte hemijske reakcije sa anjonsko-izmenjivačkom funkcijom. Ispitivanja su vršena u šaržnom i protočnom (s nepokretnim slojem) sistemu. U sklopu istaknutih zadataka i ciljeva, ispitivanja u okviru teze su bila fokusirana na: I) razdvajanje As(III) i As(V) vrsta (u cilju određivanja obe ove vrste čije prisustvo preovlađuje u prirodnim vodama), II) razdvajanje organskog arsena vrsta (u cilju određivanja obe ove DMAs (V) i MMAs (V) u prirodnim vodama) i III) sakupljanje, pretkoncentrisanje i uklanjanje svih arsenovih vrsta u vodi. Najvažniji doprinos ostvaren u izradi ove teze je razvoj tri metode za razdvajanje i određivanje arsenovih vrsta u vodi. Prva metoda predstavlja jednostavnu metodu za razdvajanje i određivanje iAs vrsta u prirodnim vodama i vodi za piće, što je i bio glavni zadatak u tezi. Definisani su postupci za pripremu uzoraka, za razdvajanje As(III) i As(V) vrsta, i za pretkoncentrisanje ukupnog sadržaja neorganskog arsena, iAs u protočnom sistemu, u koloni s nepokretnim slojem sorbenta. Ispitane su dve vrste smole: SBAE i HY-Fe. Definisani su i analizirani svi parametri šaržnog i protočnog sistema koji imaju najveći uticaj na jonsku izmenu i sorpciju arsena. Kiselost vode, koja igra vrlo važnu ulogu i u kontroli i prisustvu jonskih i molekulskih vrsta arsena u vodi, predstavlja važan faktor i za razdvajanju iAs arsena u vodi: podešavanjem pH vrednosti na vrednosti manje od 8,0, ostvaruje se mogućnost razdvajanja As(III) i As(V) vrsta: As(V) vrste se zadržavaju jer se nalaze u jonskom obliku, a As(III) vrste prolaze kroz kolonu bez zadržavanja jer se nalaze u molekulskom obliku. Sorpciona aktivnost čestica hidratisanog gvožđe-oksida (HFO) integrisanih u HY-Fe smolu bila je pogodna za vezivanje svih vrsta arsena u vodi, i to u širokom opsegu pH vrednosti od 5,0 do 11,0. Kapaciteti smola u protočnom sistemu računati su do tačke proboja i pri pH vrednosti od 7,50. Utvrđeno je da SBAE smola vezuje 370 µg/g As(V). HY-Fe smola vezuje 4150 µg/g As(III) i 3500 µg/g As(V). Ovi veliki kapaciteti smola predstavljaju prednost za razvoj i primenu dva postupka, jednog za razdvajanje i određivanje As(III) vrsta, sa SBAE smolom, drugog za koncentrisanje i određivanje ukupnog arsena u vodu (s HY-Fe smolom). Analitički parametri i karakteristike metode za razdvajanje i određivanje iAs vrsta u vodi su definisani: granica detekcije, LOD iznosi 0,24 µg/L, granica kvantifikacije, LOQ iznosi 0,80 µg/L, a relativna standardna devijacija, RSD %, za uzorke vode koji sadrže arsen od 10.0 do 300.0 µg/L ima vrednost u opsegu od 1,1 do 5,8 %. Druga metoda predstavlja, takođe, jednostavnu i efikasnu metodu za razdvajanje i određivanje iAs i oAs vrsta u prirodnim vodama, vodi za piće i otpadnim vodama. Ispitane su tri vrste smole: SBAE, HY-Fe i HY-AgCl. Kvantitativno razdvajanje molekulskih i jonskih vrsta iAs i oAs je ostvareno na SBAE podešavanjem pH vrednosti vode. Molekulski oblici As(III) koji su prisutni u vodi na pH vrednostima nižim od 8 ne vezuju se za SBAE smolu, što je iskorišćeno za direktno određivanje As(III) koncentracije u efluentu. HY-Fe smola je pogodna za razdvajanje DMAs(V) od svih drugih vrsta arsena. Sve arsenove vrste osim DMAs(V) zadržavaju se na smoli. Smola ima veliki kapacitet za arsenove vrste, 9000 µg/g. Selektivnost HY-Fe smole iskorišćena je za direktno određivanje DMAs(V) koncentracije u efluentu. HY-AgCl smola zadržava sve iAs vrste, a propušta oAs vrste što je pogodno za direktno određivanje koncentracije oAs u efluentu. Selektivno vezivanje arsenovih vrsta na tri tipa smola omogućilo je razvoj postupaka za merenje i proračun svih vrsta arsena u vodi, iAs i oAs. U cilju određivanja kapaciteta smola izvršena su preliminarna određivanja u šaržnom sistemu, a ti kapaciteti su provereni i potvrđeni u protočnom sistemu. Kapaciteti smola u protočnom sistemu su računati do tačke proboja, što je prvi korak u projektovanju modula za ekstrakciju u čvrstoj fazi (SPE) koji se mogu koristiti za razdvajanje i određivanje arsenovih vrsta. Treća metoda je jednostavna i efikasna metoda za razdvajanje i određivanje dimetilarsena, DMAs(V). Ispitane su dve smole: SBAE i HY-Fe. Jednostavnim podešavanjem pH vrednosti vode na pH 7,00, ostvareno je da DMAs(V) kvantitativno prolazi kroz kolonu sa HY-Fe bez ikakve promene u strukturi i koncentraciji. Druge arsenove vrste (neorganski arsen i monometilarsen, MMAs(V)) vezuju se kvantitativno za smolu. Kapacitet smole je veliki, smola vezuje 4150 µg/g As(III), 3500 µg/g As(V) i 1500 µg/g MMAs(V). Adsorpcija arsena neometana je od strane nečistoća ili od strane anjona koji se uobičajeno nalaze u vodi. DMAs(V) je određen u efluentu merenjem na ICP-MS-u. Detekcioni limit je bio 0,03 µg/L, a relativna standardna devijacija, RSD je bila u opsegu od 1,1 do 7,5 %. Za određivanje arsena u svim arsenovim vrstama u vodi primenjene su dve analitičke metode: induktivno spregnuta plazma sa masenom spektrometrijom (ICP-MS) i atomska apsorpciona spektroskopija s generisanjem hidrida (GH-AAS). Metode su ustanovljene na osnovu standardnih analitičkih postupaka (pripremom standardnih rastvora, analizom sertifikovanih referentnih materijala i metodom standardnog dodatka), a izvršena je i provera paralelnim merenjem nekoliko uzoraka primenom HG-AAS tehnike. Verifikacija sa sertifikovanim referentnim materijalma potvrdila je da su eksperimentalno dobijene vrednosti za model rastvor i rastvore realnih uzoraka u saglasnosti. Merenja na ICP-MS-u imala su granicu detekcije 0,2 µg/L i relativnu standardnu devijaciju (RSD) za sve ispitivane arsenove vrste u opsegu od 3,5 do 5,1 %. Analiza interferentnih, ometajućih anjona koji su karakteristični za prirodne vode je pokazala da se njihov uticaj na određivanje arsena predloženim metodama može zanemariti. Obe predložene metode mogu da se preporuče za rutinsko praćenje i analizu arsena u različitim uzorcima vode od vode za piće, podzemnih voda do zagađenih, otpadnih voda. Ključne reči: arsen, specijacija, separacija-razdvajanje, određivanje, pretkoncentrisanje, jonska izmena, hibridne smole, jonoizmenjivačke smole, ICP-MS Šira naučna oblast: Hemija Uža naučna oblast: Analitička hemija About the thesiss (important dates and structure) This thessis is accomplished at the Department of Analytical Chemistry and Quality Control at the Faculty of Technology and Metallurgy, University of Belgrade during 2008-2012 under the supervision of prof. dr Ljubinka Rajaković. Organization of the thesis The thesis comprises of seven chapters: 1) the introduction, 2) the theoretical part, 3) the experimental part, 4) the results and the discussion of results, 5) the conclusion and 6) the references. Each chapter explains and clarifies scientific work in standard manner for PhD thesis: • In the introduction the main objects of thesis, the goals and the contributions of thesis are explained. • Theoretical part comprehends the chemistry of arsenic, methods used for determination and separation of arsenic species from drinking water. Part of theoretical chapter is devoted to review of papers and research which present state-of- art in the field of arsenic investigations. • Experimental part describes new methods and procedures for determination and selective separation of arsenic species from water. Established methods that include coupling of separation techniques such as IC, HPLC for the separation of arsenic species with a sensitive detection system such as ICP-MS, HG-AFS, and HG-AAS are discussed and the choice for routine determination of a large number of water samples was explained. As the most appropriate tool for arsenic determination, ICP-MS is applied in this work for real water samples containing As(III) and As(V) species. In the lack of coupled tools, a simple procedure for arsenic species separation on exchange resins was developed and proposed. • Within the conclusion the final outcome of the thesis is written and explained. • The references which are related to the topic are listed in sixth chapter. Criterions for the choice of references were contemporary approach for arsenic analysis, the influence of recent investigations to work within this thesis and also the published results. • In order to have clear review of figures and tables, list of figures and tables is given. Belgrade 2012. Author The main achievement and contribution of the thesis The main achievement of thesis is that three methods for arsenic species determination were developed. First method is a simple method for the separation and determination of iAs species in natural and drinking water which was the main task of the thesis. Second method is a method for the separation and determination of iAs and oAs species in natural, drinking and waste water Third method is a method for the separation and determination of dimethylarsenate in natural waters. For each method a scientific paper is published. Papers published during thesis creating: 1. N.B. Issa, V.N. Rajaković-Ognjanović, B.M. Jovanović, Lj.V. Rajaković, Determination of Inorganic Arsenic Species in Natural Waters-Benefits of Separation and Preconcentration on Ion Exchange and Hybrid Resins, Anal. Chim. Acta, 673 (2010) 185-193 2. N.B. Issa, V.N. Rajaković-Ognjanović, A. Marinković, Lj.V. Rajaković, Separation and Determination of Arsenic Species in Water by Selective Exchange and Hybrid Resins, Anal. Chim. Acta, 706 (2011) 191-198 3. N.B. Issa, A.D. Marinković, Lj.V. Rajaković, Separation and determination of dimethylarsenate in natural waters, J. Serb. Chem. Soc., 77 (6) (2012) 775–788 CONTENTS Abstract Abstract in Serbian About the thesiss (important dates and structure) The main achievement and contribution of the thesis I. INTRODUCTION 1 The aim of the thesis 1 II. THEORETICAL PART 4 2.1 Chemistry of arsenic 4 2.1.1 Arsenic species in water 5 2.1.2 Effect of pH and Eh on the distribution of arsenic species in water 7 2.2 Analytical methods for the determination of arsenic in water 8 2.2.1 Analytical methods for the determination of total arsenic in water 9 2.2.1.1 Inductively coupled plasma mass spectrometry (ICP-MS) 9 2.2.1.2 Spectrophotometric methods 13 2.2.1.3 Electrochemical methods 14 2.2.1.4 Gutzeit Method 15 2.2.2. Analytical methods for the determination of arsenic species in water 15 2.2.2.1 Speciation of arsenic compounds 15 2.2.2.2 Hydride generation atomic absorption/Atomic fluorescence spectroscopy 17 2.2.2.3 Chromatography methods 20 The most common chromatography methods 21 Ion exchange chromatography 23 Classic column chromatography 25 Solid phase extraction 27 High performance liquid chromatography (HPLC) 29 2.2.3 Analytical methods for the preconcentration of arsenic species from water 32 2.2.4 Analytical methods for the preparation of samples for speciation analysis 34 2.2.4.1 Acid Digestion 34 2.2.4.2 Extraction methods 36 2.3 Evaluation of analytical results 37 2.4 Review of the arsenic speciation research on science direct 41 2.5 Theoretical approach in analysis of systems for the ion-exchange and sorption of arsenic from water 41 2.5.1 Batch system, capacity, kinetics and adsorption isotherms 43 2.5.2 Flow system, capacity and breakthrough curves 43 III. EXPERIMENTAL PART 45 3.1 Reagents apparatus and materials 45 3.1.1 Reagents 45 3.1.2 Apparatus 46 3.1.3 Glassware Cleaning Procedures 46 3.2 Analytical methods and instrumentation 47 3.2.1 ICP-MS method and procedure 47 3.2.1.1 Interferences during the ICP-MS measurements 48 3.2.1.2 Analytical figure of merit and application 48 3.2.2 HG-AAS method and procedure 49 3.3 Set-up for ion-exchange and sorption processes and procedures 49 IV. RESULTS AND DISCUSSION 51 4.1 Preliminary investigations of ion-exchange and sorption processes of arsenic species in batch system 51 4.1.1 Effect of pH values on ion-exchange and sorption processes 51 4.2 Preliminary investigations of ion-exchange and sorption processes of arsenic species in flow system 56 4.2.1 Determination of capacity of ion-exchange and hybrid resins 56 4.3 Concentration, separation and determination of arsenic species (iAs and oAs) in flow system on ion-exchange and hybrid resins with standard arsenic model Solutions in deionized water and modified water with common inorganic ions 60 4.3.1 Concentration, separation and determination of iAs on SBAE 60 4.3.2 Concentration, separation and determination of total iAs on HY-Fe 65 4.3.3 Concentration, separation and determination of oAs on HY-AgCl 67 4.3.4 Concentration, separation and determination of dimethylarsenate DMAs(V) 70 4.4 Interferences on determination of iAs and oAs species in water 72 4.4.1 Interference effect on determination of As(III) and As(V) 72 4.4.2 Interference of inorganic ions on determination of dimethylarsenate DMAs(V) 74 4.4.3 Interference of inorganic ions on determination of oAs species 75 4.5 Effect of temperature on determination of iAs and oAs species 75 4.6 Analytical properties of new procedures for preconcentration, separation and determination of As(III), As(V), MMAs(V), DMAs(V) species in standard solution 77 4.7 Analytical properties of new procedures for preconcentration, separation and determination of arsenic species in real drinking water and river water 80 4.7.1 Application of proposed methods for determination of As(III) and As(V) in real drinking water and river water 81 4.7.2 Application of proposed method for determination of organic arsenic oAs species in real drinking water 82 4.7.3 Application of proposed method for determination of dimethylarsenate DMAs(V) in drinking water 83 V. CONCLUSION 85 VI. REFERENCES 89 ƒ References based on thesis • Biography LIST OF FIGURES Figure Page 2.1 Arsenic species in water 6 2.2 Stability and speciation of arsenic compounds, As(III), As(V), DMAs(V) and MMAs(V), as a function of pH. 7 2.3 Octopole reaction cell in Agilent 7500ce ICP-MS 10 2.4 Approximate range of elements that can be analyzed using the 7500ce ICP/MS. Carbon, phosphorous, and sulfur can be analyzed with high sensitivity in specific matrices using GC-ICP/MS. 12 2.5 Agilent 7500ce ICP-MS calibration curve 13 2.6 Scheme for separation arsenic species using classic column chromatography 27 2.7 Ion analysis (HPLC) components 29 2.8 Scheme of separation and determination of arsenic species by using HPLC System 32 2.9 HPLC–ICP-MS chromatograms (anionic column) 37 2.10 The percentage of the total research for determination of arsenic species in the last four years 41 2.11 The percentage of the development of methods for determination of arsenic species in the last four years 41 2.12 Schematic presentation of reaction between arsenic species and iron 42 4.1 The effect of pH in separation of iAs on the SBAE 52 4.2 The effect of pH in preconcentration of total arsenic on HY-Fe 53 4.3 Schematic reactions of arsenic species with HY-Fe 53 4.4 The effect of pH in separation of oAs on HY-AgCl 54 4.5 The effect of pH in separation and preconcentration of iAs on SBAE and HY- Fe resins 55 4.6 Breakthrough curves for iAs species in deionized and modified tap water on SBAE 57 4.7 Breakthrough curves for iAs species in deionized and modified tap water on HY-Fe 58 4.8 Breakthrough curves for iAs and oAs species in deionized water on HY-AgCl 59 4.9 Breakthrough curves for iAs and oAs species in deionized and modified tap water on HY-Fe resin: a) deionized water and b) modified tap water 60 4.10 Breakthrough curves for iAs and oAs species in deionized water on SBAE and HY-Fe resins 73 4.11 The effect of temperature on determination of arsenic species 76 4.12 Scheme for selective separation and determination of the arsenic species in water using SBAE, HY-Fe and HY-AgCl resins 79 LIST OF TABLES Table Page 2.1 Common inorganic and organic As species 4 2.2 Approximate values for the pKa of arsenic species 5 2.3 A review of the most common chromatographic methods 22 2.4 The most common chromatographic methods related to the mechanism 23 2.5 A review of some procedure for (Extraction/Separation) of arsenic speciation 33 2.6 The comparison of the matrix effect on determination of arsenic 39 2.7 The comparison of the detection limits of arsenic species by different methods 40 3.1 Optimal instrumental operating conditions (ICP-MS Agilent 7500ce) 47 3.2 Analytical characteristics of the proposed method 49 4.1 Results of determination of As(III) by separation procedure with SBAE applied to standard arsenic solutions without adding As(V) 62 4.2 Results of determination of As(III) by proposed methods with SBAE applied to standard arsenic solutions in the presence of As(V) 62 4.3 Results of the proposed methods for determination of As(III) by SBAE applied to standard arsenic solutions in the presence of different concentration of As(V) 63 4.4 Analytical data of the proposed separation procedure using SBAE resin and determination of As(III) species in standard solutions by the ICP-MS and HG- AAS technique 64 4.5 Results of the proposed methods for determination of As(III) by SBAE applied in modified water 64 4.6 Results of the preconcentration and determination of total inorganic arsenic species applied in standard arsenic solutions 66 4.7 Analytical performance data of the proposed preconcentration procedure using HY-Fe resin and determination of the total concentration of As in standard solutions. 66 4.8 Results of the proposed methods for determination of total arsenic applied in modified water 67 4.9 Analytical data of the separation and determination of total oAs species using HY-AgCl resins in standard solutions without adding inorganic arsenic species 68 4.10 Analytical data of the separation and determination of oAs species using HY- AgCl resins in standard solutions in the presence of iAs species. 69 4.11 Analytical data of the separation and determination of oAs species using HY- AgCl resins in modified water 69 4.12 Analytical data of the separation and determination of DMAs(V) species using HY-Fe resins in standard solutions 70 4.13 Analytical data of the separation and determination of DMAs(V) species using HY-Fe resin in standard solutions in the presence of MMAs(V). 71 4.14 Analytical data of the separation and determination of DMAs(V) species using HY-Fe resins in standard solutions in presence of MMAs(V), As(V) and As(III). 71 4.15 Results of the proposed methods for determination of DMAs(V) applied to modified of water 72 4.16 The concentration (mg/L) of anions in tap water determined by HPLC 74 4.17 Concentration of interfering ions in modified tap water samples determined by HPLC 75 4.18 Result for determination of As(III) in standard solution by proposed method using SBAE at different temperature (40°C and 80°C) 76 4.19 Result for determination of iAs species in standard solution by proposed separation method using HY-Fe at different temperature (40°C and 80°C) 76 4.20 Result for determination of DMAs(V) in standard solution by proposed method using HY-Fe at different temperature (40°C and 80°C) 77 4.21 Result for determination of oAs species in standard solution by proposed method using HY-AgCl at different temperature (40°C and 80°C) 77 4.22 Results of the proposed separation procedure by SBAE, HY-Fe and HY-AgCl resin applied for the standard arsenic solutions 80 4.23 Results of arsenic analysis of real water samples by the proposed separation method using SBAE resin, n = 3 81 4.24 Results of arsenic speciation analysis of real water samples by proposed separation method using SBAE, HY-Fe and HY-AgCl resins 83 4.25 Analytical data of the determination of DMAs(V) species using HY-Fe and SBAE resins in tap water and Modified tap water containing MMAs(V), As(V) and As(III) 84 ABBREVIATIONS AAPTS 3-(2-aminoethylamino) propyltrimethoxysilane AAS atomic absorption spectrometry AAS-GH atomic absorption spectroscopy-hydride generation AES atomic emission spectrometry AFS atomic fluorescence spectrometry AM ammonium molybdate amu atomic mass unite APDC ammonium pyrrolidinedithiocarbamate Ar argon As arsenic As(III) arsenite As(V) arsenate AsB arsenobetaine AsC arsenocholine ASV anodic stripping voltammetry o C degree Celsius CNFs: carbon nanofibers CSV cathodic stripping voltammetry CTAB cetyltrimethylammonium bromide DDTC diethyldithiocarbamete DEAE- diethylaminoethyl DMAs(V) dimethylarsenic acid DMAs(III) dimethylarsinous acid DNPS 2,3-dimercaptopropane-1-sulfonate DPCSV differential pulse cathodic stripping voltammetry EBV empty bed volume Eh redox potential FI flow injection GC gas chromatography GF-AAS graphite furnace atomic absorption spectrometry g gram hr hour H3AsO3 arsenic acid HAsO2 arsenous acid HG-AFS hydride generation atomic fluorescence spectrometry HG-ICP-OES hydride generation-inductively coupled plasma atomic emissiospectrometry HMDE hanging mercury drop electrode HPLC-ICP-AES high performance liquid chromatography linked to inductively coupled plasma atomic emission spectrometry HPLC-ICP-MS high performance liquid chromatography linked to inductively coupled plasma mass spectrometry HR high resolution HS-SDME-ET-AAS headspace single drop micro extraction coupled to electro therma atomic absorption spectrometry HY hybrid resins HY-AgCl silver chloride resin HY-Fe (HFO) hydrated iron oxides iAs inorganic arsenic species ICP inductive coupled plasma ICP-AES inductively coupled plasma atomic emission spectrometry ICP-MS inductively coupled plasma mass spectrometry ICP-OES inductively coupled plasma optical emission spectrometry K kelvin L liter LC liquid chromatography LOD limit of detection LOQ limit of quantification m mass M molar mg milligram min minute mL millilitre mm millimeter MMAs(V) monomethilarsenic acid MMAs(III) monomethylarsonous acid mol mole MRT polymeric organic materials-ion –selective MS mass spectra m/z mass to charge ratio MΩ.cm megaohm×centimeter µg micrograms ng nanogram oAs organic arsenic species OES optical emission spectrometry PAS phenylarsonic acid PDC pyrrolidine dithiocarbamate pKa dissociation Constant ppm parts per million PTFE polytetrafluoroethylene P(V) phosphate (V) Q flow rate RC–GLS reaction chamber/gas–liquid separator RF radio frequency rmp rotations per minute RSD relative standard deviations SBAE strong base anion exchange resin SEC-ESI-MS size exclusion chromatography coupled to electrospray ionization mass spectrometry σ standard deviation SPE solid phase extraction SWCNTs single-walled carbon nanotubes TETRA tetramethylarsonium ion t temperature TMAO trimethylarsine oxide TMAs+ tetramethylarsonium ion TPAC tetraphenylarsenium chloride Triton-Cp non ionic surfactants TXRF total Reflection X-Ray Fluorescence τ time ULOQ upper limit of quantification V volume w/v weight per volume I INTRODUCTION 1 I INTRODUCTION The object of the thesis was arsenic in water. Arsenic, As, is a metalloid. Arsenic’s history in science, medicine and technology has been overshadowed by its feature as a poison. Arsenic is a synonym of toxicity. Arsenic exists in the –3, 0, +3 and +5 oxidation states [1]. These oxidation states cause arsenic to be very reactive and affect its physical and chemical behavior. The different chemical species or forms (speciation) of As exhibit different degrees of toxicity. The term speciation is also used to indicate the distribution of species in a particular sample or matrix. Arsenic is widely distributed throughout the environment. It is present in biota, the atmosphere, oceans, lakes, groundwater, sediments, and soils throughout the world. Arsenic is present in many minerals. Due to high mobilization of arsenic, both from natural and anthropogenic sources, it is reactive in aquatic environments and the atmosphere. Natural sources of arsenic mobilization include weathering of arsenic-bearing rocks, biological activity, and volcanic eruption. Anthropogenic sources include mining of metal ores, combustion of fossil fuels, pesticide, livestock feed additives, wood preservatives, and pigment production. In most cases of groundwater contamination, however, a combination of natural and anthropogenic actions leads to arsenic release [2]. Water soluble arsenic species existing in natural water are inorganic arsenic (iAs) species as arsenite, As(III) and arsenate, As(V) and organic arsenic (oAs) species as monomethilarsonic acid, MMAs(V) and dimethylarsinic acid, DMAs(V) [3]. In aquatic systems, inorganic arsenic, iAs, are the most prevalent forms, although oAs as methylated arsenic species is generated by aquatic biota in trace concentrations [3]. For the selective separation of arsenic species in these thesis three types of resins were investigated: a strong base anion exchange (SBAE) resin and two hybrid (HY) resins based on activity of hydrated iron oxides, HY-Fe, and silver chloride, HY- AgCl. Two systems were employed: a batch and a fixed bed flow system. The aim of the thesis was to develop methods for the determination and selective separation of arsenic species from water. Speciation analysis is defined as the determination of the various chemical (oxidation/valence states) forms of the element which together make up the total concentration of that element on a sample. Speciation analysis is aiming to define and quantify the distribution of an element between the different species in which it occurs [1,4]. These structural levels are important in different areas, for instance, valence state and inorganic and organic speciation are of great importance in determining the availability and 2 toxicity of metals or metalloids, thus being very important in food, and also in clinical and biological fields. Concerning arsenic, the different chemical species or forms of As completely depends on the pH value. Applying this concept to the arsenic species in water, one of the tasks in the thesis was to establish procedure for the separation and determination of iAs and oAs species in water. The investigations were focused on As(III) (in water it exists as: H3AsO3, HAsO32- and AsO33-), As(V) (in water it exists as: H3AsO4, H2AsO42- and AsO43-), MMAs(V) and DMAs(V) as typical and prevailing arsenic species in water. The use of hyphenated analytical techniques for on-line separation and determination of species are highly recommended, but in the lack of these highly sophisticated techniques an individual, intelligent strategy can be developed for selective and sensitive determination of species. In order to separate arsenic species before analytical determination a non-chromatographic speciation method was applied, sorption on multifunctional ion-exchange and sorption materials. Three types of solid have been used: a strong base anion exchage (SBAE) resin and hybrid (HY) resins: HY-Fe and Hy-AgCl. The investigations performed in the experimental work were focused on: I) separation of iAs (As (III) and As(V)) in order to determine both arsenic species which are prevailing in natural water and compare with total arsenic content in water sample), II) separation of iAs and oAs (in order to determine all inorganic and organic arsenic species which can be present in water and wastewater due to antrophogenic influence) and III) collection, preconcentration and removal of all arsenic species from water. As the most appropriate tool for arsenic determination, ICP-MS was applied in the work for real water samples containing iAs and oAs species at low µg/L. The contribution of the thesis is the development and application of methods for determination of arsenic speciec in natural and drinking water and their removal. Methods are based on coventional ion-exchange resins and new hybrid, HY, resins which integrate the anion exchange function with sorption and chemisorption on hydrated iron oxides, HY-Fe and silver chloride, HY-AgCl. Proposed methods could be applied routinely for monitoring arsenic levels in various water samples (drinking water, ground water and wastewater) and they are the base for the development of procedures for arsenic removal from water sources for drinking water. 3 The separation and preconcentration procedures were well coordinated with the ICP-MS technique for a sensitive determination of the total As concentration and iAs and oAs species at low µg/L. Measurements with certified reference materials proved that the measurements of arsenic species concentrations in model solutions and real samples were in agreement with the certified values. Both methods could be applied routinely for monitoring of arsenic levels in various water samples (drinking water, ground water and wastewater). Available commercial arsenic removal technologies include adsorption, precipitation, membrane and hybrid membrane processes. Among them, sorption is considered to be relatively simple, efficient and low cost removal technique, especially convenient for application in rural areas. Wide range of sorbent materials for aqueous arsenic removal is available nowadays: biological materials, mineral oxides, different soils, activated carbons and polymer resins. Nevertheless, finding cheap and effective arsenic sorbent is still highly desired. Sorption by materials containing iron oxide is an innovative technology for purifying drinking water contaminated by toxic metal pollutants. The present focus on arsenic removal in the developing countries is the use of iron containing compounds because they are both economical and effective. 4 II THEORETICAL PART 4 II THEORETICAL PART 2.1 CHEMISTRY OF ARSENIC Arsenic is a metalloid element, with a chemical symbol As, has two allotropes: grey (density 5.73 g/cm3 at 300 K) and the yellow forms (1.97 g/cm at 300 K). The grey form is the most common and more stable, the atomic number of arsenic is 33 and atomic weight 74.92 g/moL. It sublimes at 617 °C. Its electronic configuration is [Ar]18 4s2 3d10 4p3. It occurs in several oxidation states (-3, 0, +3, +5) under different redox conditions. It oxidizes rapidly in oxygenated media to form AsO33- [arsenite, As(III)], or AsO43- [arsenate, As(V)] depending on the pH and redox potential of its surrounding. Substitution of oxygen atoms with methyl group leads to the formation of monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) [5,6]. In table 2.1 common inorganic and organic arsenic species are noted. The inorganic species tend to be more prevalent in water than the organic arsenic species [7]. While the organic species (methylated arsenic) are commonly considered to be of little significance in waters compared with the inorganic species [2,8,9,10]. Table 2.2 shows the approximate values for the pKa of arsenic species. Table 2.1 Common inorganic and organic As species [4] Name Synonyms Oxidation State Chemical Formula Arsenate As(V) +5 AsO43- Arsenite As(III) +3 AsO33- Methylarsonic acid Monomethylarsonic- - acid, MMA +5 CH3AsO(OH)2 Dimethylarsinic acid Cacodylic acid, DMA +5 (CH3)2AsO(OH) Trimethylarsine oxide TMAO +5 (CH3)3AsO Tetramethylarsonium ion TETRA +3 (CH3)4As+ Arsenobetaine AsB +3 (CH3)3As+CH2COO- Arsenocholine AsC +3 (CH3)3As+CH2CH2OH 5 Table 2.2 Approximate values for the pKa of arsenic species H3AsO4 H+ + H2AsO4 - H2AsO4 - H+ + HAsO42- HAsO42- H+ + AsO43- H3AsO3 H+ + H2AsO3 - H2AsO3 - H+ + HAsO32- HAsO32- H+ + AsO33- H2AsO3(CH3) H+ + HAsO3- (CH3) HAsO3- (CH3) H+ + AsO32- (CH3) HAsO2(CH3)2 H+ + AsO2- (CH3)2 As(V) As(III) MMAs(V) DMAs(V) Speciation Equation pKa 2.24 6.69 11.5 9.20 12.1 13.4 4.49 8.77 6.14 2.1.1 Arsenic species in water Arsenic of geological origin is found in groundwater used for drinking-water supplies in several parts of the world. Arsenic occurs in several different species depending upon the pH and oxidation potential of the water; inorganic arsenic occurs in two valence states, inorganic arsenic “arsenite As(III) and arsenate As(V)” mostly found in natural waters, for both ground waters and surface waters While the methylated species would rarely be present in water supplies [2]. Organic arsenic forms may be produced by biological activity, mostly in surface waters, but are rarely quantitatively important such as MMAs(V) and DMAs(V) are predominant in water and sediments [3,8,9], and both organic arsenic DMAs(V) and MMAs(V) stable in oxidizing system [3]. 6 One of the most important sources of arsenic is leaching of naturally occurring arsenic into water aquifers resulting in run off of arsenic into surface waters. Drinking water is derived from a variety of sources depending on local availability: surface water (rivers, lakes, reservoirs and ponds), groundwater (aquifers) and rain water. Several anthropogenic activities including coal combustion, irresponsible disposal of mine tailings, glassware and ceramic industries, petroleum refining, dyes and pesticides contribute to elevated arsenic levels in the water. The WHO guideline for arsenic in drinking water is 10µg/L. The development of simple and easy methods for determination of arsenic in water becomes a priority in research. New inexpensive methods which can provide acceptable quantitative results are very important for research studies in the field of analytical chemistry. In Fig. 2.1 the structural difference between arsenate and arsenite in waters is shown. As O OH OH CH3 CH3 As O OH HO OHAs OH HO O OHAsHO CH3 O AsHO Arsenious acid Arsenic acid Monomethylarsonic acid Dimethylarsinic acid Fig. 2.1 Arsenic species in water [3,8] 7 2.1.2 Effect of pH and Eh on the distribution of arsenic species in water pH and redox potential (Eh) play the primary and (the most) important role in determining and separating arsenic species. As(V) species are dominant under oxidizing conditions, and As(III) is thermodynamically stable under mildly reducing conditions. Thus As(V) is more likely to occur in surface waters and As(III) tends to occur more frequently in ground waters. As(III) is more mobile because it is present as a neutral form at the pH of most natural ( 4.0, but significant efficiency was reached at pH > 6.0. At higher pH values divalent As(V) ions prevail and a higher separation efficiency was exhibited. As(III) did not bond to the SBAE resin at pH < 8.0 due to the existence of neutral molecules of As(III) below this pH value. With this feature the SBAE resin is a convenient material for the separation of As(III) and As(V) species. As(V) could be bonded totally to the SBAE by adjusting the pH value, As (III) determined easily without interference. 52 As(V) As(III) 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 8 9 10 11 12 pH A ds or be d ( % ) Fig. 4.1 The effect of pH in separation of iAs on the SBAE, Conditions: CAs(III) = CAs(V) = 100.0 mg/L, mresin = 1.00 g, t = 20 °C, V = 100 mL, τ= 60 min, w = 150 rpm, n = 5 4.3.1.2 Effect of pH on hybrid resin HY-Fe for preconcentration of total arsenic Preconcentration of all iAs species to the HY-Fe resin in order for determine of total iAs as an analyte or to remove iAs as an interference in analytical determinations. The Fig. 4.2 showed that the inorganic arsenic species (iAs) separation from water by the HY-Fe resin was not affected by the pH value, suggesting that HY-Fe is efficient for the preconcentration and mutual interference removal of molecular and ionic forms of both As(III) and As(V). At equilibrium (CAs = 100 mg/L, V = 100 mL, room temperature, τ = 24 h, w = 150 rpm), pH value was between 2.0 and 12. The results confirmed that under neutral conditions, which are a feature of natural and drinking water, both of inorganic species were bonded according to the reaction in schematic Fig.4.3 at pH value 5.0-10. However, preconcentration and determination of total arsenic species could be preformed At pH value between 6.5 to 8.5. 53 As(V) As(III) 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 8 9 10 11 12 pH A ds or be d (% ) Fig. 4.2 The effect of pH in preconcentration of total iAs on HY-Fe, Conditions: CAs(III) = CAs(V) = 100.0 mg/L, mresin = 1.00 g, t = 20 °C, V = 100 mL, τ= 60 min, w = 150 rpm, n = 5 Fig. 4.3 Schematic reactions of arsenic species with HY-Fe 54 4.3.1.3 Effect of pH on HY-AgCl for separation and determination of oAs species In order to elucidate the influence of pH values of water to separation ability of HY−AgCl resin in the preliminary investigations some experiments were accomplished in a batch system. The procedure at the following conditions: mass of resin (m = 1.0 g), concentration of all arsenic species (CAs = 500 µg/L), volume of water solution (V = 100 mL), temperature (t= room temperature), contact time (τ = 60 min) and shaker speed (w = 150 rpm) were constant during the experiments. The results are presented in Fig. 4.4 The presented results in figure 4.4, confirmed that the separation of inorganic and organic arsenic species by HY−AgCl resin is highly affected by the initial pH of working solution. The organic arsenic species are not bonded with HY−AgCl. It can be ascribed to the steric interference with a surface groups, repulsive forces prevent to some extent entrance inside the meso and micropores [152]. As(III) and As(V) species were bonded with HY−AgCl at pH value 4.0−12, but the maximum sorption was noticed at pH 9.0. With this specific feature, the HY−AgCl resin is a convenient material for the separation of iAs and oAs (V) species at pH 9.0 As(III) As(V) MMAs(V) DMAs(V) 0 10 20 30 40 50 60 0 2 4 6 8 10 12 pH A ds or be d (µ g/ g) Fig. 4.4 The effect of pH in separation of oAs on HY-AgCl resins, Conditions: CAs(in all species)=500 µg/L, mresin=1.0 g, t=20 oC, V=100 mL, τ=2hr, w=150 rpm 55 4.3.1.4 Effect of pH on HY-Fe for separation and determination of DMAs(V) The influences of pH on the separation of arsenic species iAs and oAs was studied in a pH rage from 2.0 to 12, the results are given in Fig. 4.5. Separation of the iAs and oAs species was conducted, using HY-Fe and SBAE resins, in a batch system procedure at the following conditions: mass of the resin (m = 1.0 g), sample volume (V = 100 ml), concentration of both oAs and iAs CAs=(100 mg/L), contact time (τ = 60 mim) and shaker speed (w = 150 rpm) at room temperature. All capacities measurements were done in triplicate. The results presented at Fig. 4.5, show that the pH of solution plays an important role in the control of arsenic species which is beneficial for the arsenic separation. SBAE can be high efficiency used for separation and determination of As(III) and As(V). Bonding capacities of SBAE with respect to MMAs(V), DMAs(V) and As(V) species increase starting from pH 5.0 and reach maxima at pH 11.0. However The SBAE bonded all arsenic species at neutral pH value except As(III) - as mentioned in Figure 4.5. 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 8 9 10 11 12 pH A ds or be d ( % ) SBAE:As(V) SBAE:As(III) SBAE:MMAs(V) SBAE:DMAs(V) HY-Fe:As(V) HY-Fe:As(III) HY-Fe:MMAs(V) HY-Fe:DMAs(V) Fig. 4.5 The effect of pH in separation and preconcentration of iAs on SBAE and HY-Fe resins Conditions: CAs(III) = CAs(V) = CMMAs(V) = CDMAs(V) = 100.0 mg/L, mresin = 1.00 g, t = 20 °C, V = 100 mL, τ = 60 min, w = 150 rpm The DMAs(V) exist as neutral species, or even as cation in strongly acidic media [102], at pH < 6.0 Fig. 4.5, at pH 7.0 DMAs(V) is not bonded at HY-Fe, while MMAs(V) shows significant affinity to HY-Fe resin surface. Significant sorption capacity of MMAs(V) was 56 observed in a pH range from 6.0 to 10.0 and at lower pH molecular forms become dominant and less attracted by positive resin surface. Low DMAs(V) sorption capacity at pH > 8.0 could be due to steric interference of two methyl and resin surface groups, and those repulsive forces prevent entrance inside meso- and micropores [152]. Arsenate adsorption on iron-oxide involves ligand exchange reaction with surface hydroxyl group, which result in different surface complexes, e.g., monodentate vs bidentate, mononuclear vs binuclear. Arsenite adsorbs via ligand exchange reaction as well forming mono- and binuclear complexes. At higher surface coverage bidentate binuclear complex is a preferential type of binding which could be a reason of low affinity of DMAs(V) toward HY-F resin surface [153,154]. However, iAs and MMAs(V) separation from water by the use of HY-Fe resin was not affected by the pH value suggesting that HY-Fe is efficient for the retained of molecular and ionic forms of both As(III), As(V), as well MMAs(V). While DMAs(V) did not bond to the HY-Fe resin at pH < 8.0. From that point of view HY-Fe resin could be used, without interference with other arsenic species, in the pH range from 6.0 to 8.0 for separation and determination of DMAs(V). Generally, preconcentration of iAs and MMAs(V) species to the HY-Fe resin could be performed in order to determine DMAs(V). 4.4 PRELIMINARY INVESTIGATION OF ION-EXCHANGE AND SORPTION PROCEDURE OF ARSENIC SPECIES IN FLOW SYSTEM The fixed bed flow system employed laboratory columns of diameter 2.00 cm. The flow rate, Q, mass of resins, m, and empty bed volume, EBV, were adjusted to obtain optimal time of contact, τ, for the ion exchange/sorption. The exchange/sorption capacity was determined according to the following equation: q = i fC C V m − (4.1) where: q - sorption capacity (mg/g), Ci - initial arsenic concentration (mg/L), Cf - final arsenic concentration (mg/L), V – volume of model solution (L) and m - mass of resin (g). 4.2.1 Determination of capacity of ion-exchange and hybrid resins 4.2.1.1 Determination of ion-exchange SBAE on separation of inorganic arsenic species Before analytical application, resin was exposed to the preliminary investigations in standard fixed bed flow system. In order to find out the capacities and the efficiency of the resins for the separation and determination, the collection purposes high arsenic concentration of 5000 57 µg/L, was tested. Each arsenic species was tested and analyzed separately. In all experiments the conditions were: CAs(III) = CAs(V) = 5000 µg/L, pH = 7.5, mresin = 6.0 g, Q = 1.66 mL/min, EBV= 12.5 mL. Breakthrough point (the point when the arsenic concentration is equal or higher than 10 µg/L was an optimal criteria for the comparison of different sorbents. The main results obtained with resin and iAs species in deionized and modified tap water are presented in Fig. 4.6. The result presented that the SBAE resin in flow system bonds more than 370 µg/g of As(V), while As(III) is not bonded at all. The results presented that the SBAE can be used as separation method for As(III) and As(V) and can be simply measured of As(III). Fig.4.6. Breakthrough curves for iAs species in deionized and modified tap water on SBAE: a) deionized water; b) modified tap water (influence of common inorganic ions) 4.2.1.2 Determination of hybrid resin HY-Fe on separation of total inorganic arsenic species In order to find out the capacities and the efficiency of the HY-Fe for the preconcentration and determination of total inorganic arsenic, high arsenic concentration of 5000 µg/L, was tested. In all experiments the conditions were: Concentration of both arsenic were CAs(III = CAs(V) = (5000 µg/L), pH = 7.5, mass of resin was (mresin= 6.0 g), flow rate (Q = 1.66 mL/min) and EBV = 12.5 mL, n = 3 The results in the Fig. 4.7 presented that, the HY-Fe resin bonds more than 4150 µg/g of As(III) and more than 3500 µg/g of As(V) over a wide range of pH values. The capacities of the resins were slightly lower when modified tap water was tested. The quantity of bonded arsenic was calculated only up to the breakthrough point. These high capacities of resins are a) As(III) As(V) 0 50 100 150 200 250 300 350 400 0 100 200 300 400 500 600 700 Volume (mL) A s ( µg /L) b) As(V) As(III) 0 50 100 150 200 250 300 0 100 200 300 400 500 600 700 Volume (mL) A s ( µg /L ) 58 b) As(III) As(V) 0 50 100 150 200 250 300 350 400 450 0 1000 2000 3000 4000 5000 6000 Volume (mL) A s ( µg /L ). very convenient for development of analytical procedures for water sample. These results are also promising for solid phase extraction technologies and some specific pretreatment systems described in the literature [20,99,155]. Fig.4.7. Breakthrough curves for iAs species in deionized and modified tap water on HY-Fe: a) deionized water; b) modified tap water (influence of common inorganic ions) 4.2.1.3 Determination of hybrid resin HY-AgCl on separation of organic arsenic species Capacities and the efficiency of the resins for the separation and determination the collection purposes preliminary were investigated in a standard fixed bed flow system. Each arsenic species was tested and analyzed separately. The concentration of all species was prepared in order to have final arsenic concentration of 500 µg/L. In all experiments, the conditions were: CAs(III) = CAs(V) =CDMAs(V) =CMMAs(V) 500 µg/L, pH = 9.0, mresin = 6.0 g, Q = 1.25 mL/min and EBV = 12.5 mL, n = 3. Breakthrough point (the point when the arsenic concentration is equal or higher then 10 µg/L) was an optimal criteria for the comparison of different resins. The results obtained with model solutions of iAs and oAs species are presented in Fig.4.8. Retention behaviors of the arsenic species on resins were estimated comparing the species concentration in the sample solution loaded in resin columns with the concentration in the solution, which passed through the columns. Data evaluation showed that the most significant finding of this experimental part was the following a) As(V) As(III) 0 200 400 600 800 1000 1200 1400 1600 1800 0 1000 2000 3000 4000 5000 6000 Volume (mL) A s ( µ g/ L) . 59 As(V) As(III) DMAs(V) MMAs(V) 0 20 40 60 80 100 120 0 20 40 60 80 100 120 140 160 Volume (mL) A s ( µg /L ) Fig. 4.8 Breakthrough curves for iAs and oAs species in deionized water on HY-AgCl. The HY−AgCl resin bonds only iAs species [As(III) and As(V)] allowing oAs species to pass through. It could be ascribed to the chemical reaction between iAs species and silver-chloride onto HY−AgCl, at pH values near 9.0. At this pH value, MMAs(V) and DMAs(V) exist in ionic forms, but they did not exhibit the affinity to silver−chloride as active agent of HY−AgCl resin. It is interesting that DMAs(V) is recognized as a cation in acidic medium [102]. The HY−AgCl resin in batch system bonds, at pH=9.0, more than 950 µg/g of As(III) and more than 1500 µg/g of As(V). The capacity of the HY−AgCl resin in a flow system was low, 80 µg/g of As(V) and 85.0 µg/g of As(III). The capacity of HY−AgCl is an order of magnitude lower than those of other resins, but the resin was stable and efficient for arsenic separation in the case when real water sample were tested. This result is promising and worthy for the development of a specific determination, pretreatment separation system and SPE cartridges. 4.2.1.4 Determination of hybrid resin HY-Fe on separation of dimethylarsenate In order to establish method for separation and determination of DMAs(V), it was necessary to determine the capacity and the efficiency of HY-Fe resins in a fixed bed flow system. 60 b) As(V) As(III) MMAs(V)DMAs(V) 0 50 100 150 200 250 300 350 400 450 0 1000 2000 3000 4000 5000 6000 Volume( mL) A s ( µg /L ) Model solution was prepared from deionized water, conditions: CAs(III) = CAs(V) = CMMAs(V) = CDMAs(V) = 5000 µg/L, pH 7.0-7.5, mresin = 6.0 g, Q = 1.66-2.0 mL/min and EBV = 12.5 mL. The breakthrough point is the point when the arsenic concentration is equal to or higher than 10 µg/L, which is a good criterion for determination of resin capacity as well for resin comparison. The results of capacities determination for HY-Fe resins are shown in Fig. 4.9. Fig. 4.9 Breakthrough curves for iAs and oAs species in deionized and modified tap water on HY-Fe resin: a) deionized water and b) modified tap water. The capacity of HY-Fe resin, in a fixed bed flow system, for the samples prepared in deionized water was 1500 µg/g for MMAs(V), 4150 µg/g for As(III) and 3500 µg/g for As(V) at pH 7.0. Analogous experiments conducted with modified tap water gave results of slightly lower capacities (less than 10%). The high capacity provides a good area for research, especially for the separation and determination of DMAs(V) in different water samples. 4.3 CONCENTRATION, SEPARATION AND DETERMINATION OF ARSENIC SPECIES ( iAs AND oAs) IN FLOW SYSTEM ON ION-EXCHANGE AND HYBRID RESIN WITH STANDARD ARSENIC MODEL SOLUTION IN DEIONIZED AND WATER MODIFIED WITH COMMON INORGANIC IONS 4.3.1 Concentration, separation and determination of iAs on SBAE. A large number of experiments have been conducted to estimate the arsenic in standard solution samples according to the proposed procedures are presented in tables 4.1, 4.2, 4.3 a) As(V) As(III) MMAs(V)DMAs(V) 0 50 100 150 200 250 300 0 1000 2000 3000 4000 5000 6000 Volume (mL) A s ( µg /L) 61 and 4.4. Standard solutions of arsenic were prepared by the proposed procedure, the separation condition were: mresin = 6.0 g; t = 20 °C; Q = 1.66 mL/min, EBV = 12.5 mL, τ = 7.5 min, Vsample = 20 mL, n = 5 at pH 7.5. All standard solutions were measured by ICP-MS and HG-AAS method. The concentrations investigated ranged from very low, near to the drinking water (5.0 µg/L) to relatively high (100, 200 or even 300 µg/L), which are close to real water samples from the Vojvodina region. The standard solution were prepared according to the tables, table 4.1 Presents the result of determination of As(III) without any additions of As(V), while the ratio between As(III) and As(V) species were 1:1 presented in table 4.2. Table 4.3 and 4.4 show the results of As(III) at lower /higher than content of As(V) which is also related to real water samples. Table 4.5 shows the effect of ions naturally present in water. The results in Table 4.1, 4.2 and 4.3 confirmed that the As(III) as a nonionic species was not retained on the SBAE resin under the proposed conditions, whereas As(V), which is present as anionic species, was retained on the resin. After separation by SBAE, only As(III) species were present in the water and measured with ICP-MS/ HGAAS, The good recoveries percentages for all samples were obtained for determination of As(III). The proposed method described has proven to constitute an effective approach for the determination of As(III) and As(V) in standard solution samples. The methods could be applied for determination of inorganic arsenic species in water samples. 62 Table 4.1 Results of determination of As(III) by separation procedure with SBAE applied to standard arsenic solutions without adding As(V) Table 4.2 Results of determination of As(III) by proposed methods with SBAE applied to standard arsenic solutions in the presence of As(V) As concentration, µg/L Standard solutions analyzed Measured Sample As(III) As(V) Total As Total As±σ Recovery % As 1 5.00 0.00 5.00 5.10±0.08 102.0 2 10.0 0.00 10.0 9.88 ± 1.3 98.80 3 15.0 0.00 15.0 15.2±2.5 101.3 4 25.0 0.00 25.0 25.5 ± 1.4 102.0 5 50.0 0.00 50.0 48.9 ±2.0 98.00 As concentration, µg/L Standard solutions analyzed Measured Sample As(III) As(V) Total As Total As±σ Recovery % As 1 5.00 5.00 5.00 5.20±0.98 104.0 2 10.0 10.0 20.0 10.8 ± 2.5 108.0 3 15.0 15.0 30.0 14.54±2.2 97.0 4 20.0 20.0 40.0 20.5 ± 1.7 102.6 5 22.5 22.5 45.0 22.0 ±0.8 98.0 6 25.0 25.0 50.0 24.4± 2.0 97.6 7 30.0 30.0 60.0 28.5± 1.2 95.0 8 40.0 40.0 80.0 40.9 ± 1.2 102.2 9 50.0 50.0 100.0 48.9 ± 1.9 97.8 10 50.0 100 150.0 49.0± 2.1 98.0 11 10.0 75.0 85.0 10.0± 0.7 100.0 12 75.0 75.0 150.0 75.5±1.0 100.6 13 100.0 100.0 200.0 104 ± 1.5 104.0 14 150.0 150.0 300.0 150 ± 3.8 100.0 63 Table 4.3 Results of the proposed methods for determination of As(III) by SBAE applied to standard arsenic solutions in the presence different concentration of As(V) The analytical data of the proposed separation procedure for the two standard arsenic solutions are presented in table 4.4. The concentrations of arsenic species were related to relatively low (sample #1: CAs(III) = 10.0 and CAs(V) = 30.0 µg/L) and the average concentration (sample #2: CAs(III) = 20.0 and CAs(V) = 80.0 µg/L) of arsenic found in natural waters. In order to establish the separation procedure, the concentration of As(III) in the effluent was tested by the ICP-MS and HG-AAS technique. According to the results presented in table 4.4, good agreement between the ICP-MS and HG- AAS measurements was observed in determined of As(III). The standard deviations of the determination of As(III) in the two standard samples by both techniques were in the range from 0.50 to 1.10 µg/L. The maximal relative standard deviation (RSD), was about 5.6%. As concentration, µg/L Standard solutions analyzed Measured Sample As(III) As(V) Total As Total As±σ Recovery % As 1 5.00 8.00 13.0 5.20±0.98 104.0 2 5.00 10.0 15.0 4.70±0.40 94.0 3 5.00 12.5 17.5 4.85±1.20 97.0 4 5.00 15.0 20.0 4.95±2.00 99.0 5 5.00 20.0 25.0 10.8 ± 2.5 108.0 6 5.00 25.0 30.0 5.15±0.52 103.0 7 5.00 30.0 35.0 5.10±0.70 102.0 8 10.0 5.00 15.0 9.89±1.2 99.0 9 10.0 15.0 25.0 9.80±.85 98.0 10 10.0 20.0 30.0 10.11±1.3 101.0 11 20.0 40.0 60.0 21.0±2.1 105.0 12 50.0 100.0 150.0 50.12±2.3 100.4 13 10.0 5.00 15.00 10.2±1.1 102.0 14 100.0 150.0 250.0 97.5±2.5 97.6 64 Table 4.4 Analytical data of the proposed separation procedure using SBAE resin and determination of As(III) species in standard solutions by the ICP-MS and HG-AAS technique As measurements #1. #2. Standard solution analyzed As(III) As(V) As(III) As(V) Concentrations of standards (µg/L) 10.0 30.0 20.0 80.0 Measured after separation on SBAE, As(III) ICP-MS Mean 10.20 20.4 Standard deviation (µg/L) 0.47 1.10 %RSD 4.61 5.40 Confidence limit (t = 2.36 for 95% certainty 10.2±0.39 20.4±0.92 Measured after separation on SBAE, As(III) AAS-HG Mean 9.70 19.7 Standard deviation (µg/L) 0.50 1.10 %RSD 5.20 5.60 Confidence limit (t = 2.36 for 95% certainty) 9.7±0.42 19.7±0.92 Table 4.5 Results of the proposed methods for determination of As(III) by SBAE applied in modified water Table 4.5 shows the effect of ions naturally present in water on the efficiency of proposed method and ability to measure the low concentrations of arsenic species. Many experiments has conducted by adding different concentrations of ions to a sample of As(III). The results showed that there was no effect on the proposed method for determination of As(III) in the presence of common ions in the water until the concentration reached to 100 mg/L for each of the sulfate, chloride, nitrate, and bicarbonate. These results give clear evidence that the proposed method can be applied for different water types. As content, standard addition Inorganic ions added, mg/L Measured Sample As(III) SO42- Cl- NO3- HCO3- As(III)±σ Recovery % As 1 5.00 10.0 10.0 10.0 10.0 5.05±0.3 101.0 2 5.00 25.0 25.0 25.0 25.0 5.2±0.21 104.0 3 10.0 50.0 50.0 50.0 50.0 9.8.±2.5 98.0 4 10.0 100.0 100.0 50.0 150.0 9.86 ±1.0 98.6 5 50.0 100.0 100.0 100.0 110.0 51.5±2.5 103.0 65 4.3.2 Concentration, separation and determination of total iAs on HY-Fe resin 4.3.2.1 Preconcentration and determination of total arsenic in deionized water and modified water The use of HY-Fe resin for preconcentration and determination of total inorganic arsenic species were investigated, in standard solutions by the proposed procedures. The results are presented in table 4.6. The standard solutions of arsenic were prepared by the standard procedure, separation conditions by HY-Fe were: mresin = 6.0 g; temp. = 20 °C; pH = 7.50: Q = 1.66 mL/min, EBV = 12.5 mL, τ = 7.5 min, Vsample = 20 mL, n = 5. All standard solutions were measured by ICP-MS and HG-AAS instruments. The concentrations investigated ranged from very low, near to the drinking water (10.0 µg/L) to relatively high ( 300 µg/L), which are close to real water samples from the Vojvodina region. The ratio between As(III) and As(V) species was 1:1 /or the random concentration ratio between As(III) and As(V) which is also related to real water samples (table 4. 6) The use of HY-Fe resin provided a high efficiency preconcentration of As(III) and As(V) based on the bonded of iAs species with HY-Fe resin, then the arsenic eluted and measured by ICP-MS / HG-AAS without any matrix interference. Results show that the method can be efficiency used for determination of iAs with out interference. Also the proposed method can be used to prevent interference of arsenic ions in the case of determination of the other elements. Analytical data for the preconcentration procedure of all iAs species and for the desorption of arsenic from the HY-Fe resin are presented in table 4.7. The conditions for sorption and desorption of iAs from HY-Fe resin are also listed. Two standard solutions were prepared with concentrations of arsenic species which were related to extremely low (CAs(III) = 2.0 and CAs(V) = 8.0 µg/L) and average (CAs(III) = 20.0 and CAs(V) = 80.0 µg/L) concentrations of arsenic in natural waters. The data shown in table 4.7 confirmed that arsenic species could be efficiently preconcentrated and determined and removed from water. 66 Table 4.6 Results of the preconcentration and determination of total inorganic arsenic species applied in standard arsenic solutions Table 4.7 Analytical performance data of the proposed preconcentration procedure using HY-Fe resin and determination of the total concentration of As in standard solutions As measurements 1. 2. Standard solution analyzed As(III) As(V) As(III) As(V) Concentrations of standards (µg/L) 2.00 8.00 10.0 90.0 Measured after separation on HY resin Maen 10.15 105.8 Standard deviation (µg/L) 0.09 1.70 %RSD 0.89 1.61 Confidence limit (t = 2.36 for 95% certainty 10.15 ±0.08 105.8±1.42 Conditions for desorption from HY-Fe resin: pH> 11.00, V-sample =50mL. The benefit of the removal in the analytical sense is the separation and the possibility to concentrate all arsenic species on a small amount of ion exchange/sorption material (m = 6 g). The content of arsenic bonded to the resin was desorbed by a 1:1 mixture of 1.0M NaOH and As concentration, µg/L Standard solutions analyzed Measured Sample As(III) As(V) Total As Total As±σ Recovery % As 1 5.00 5.00 10.0 10.1±0.11 101.0 2 5.00 10.0 15.0 15.3±0.23 101.5 3 5.00 50.0 55.0 60.0±2.5 108.0 4 10.0 5.00 15.0 14.6 ±1.2 97.0 5 10.0 100.0 110.0 104.5±3.2 95.0 6 10.0 10.0 20.0 20.2± 1.6 101.0 7 40.0 40.0 80.0 78..0± 0.2 97.5 8 50.0 50.0 100.0 105.8 ± 1.7 105.8 9 50.0 150.0 200.0 200.0± 2.3 100 10 100.0 100.0 200.0 209.0 ± 2.6 104.5 11 150.0 150.0 300.0 296.5± 3.2 98.8 12 100.0 200.0 300.0 297.3±1.8 99.0 67 1.0M NaCl solutions using at least 3EBV of solution for evaluation. In this way, an even higher sensitivity was attained; the standard deviation of the arsenic determinations was in the range from 0.09 to 1.70 µg/L. As particulate iron is incorporated in the HY-Fe resin, the concentration of iron in the effluent was also determined by ICP-MS measurements. It was found that the concentration of iron in the effluent was no higher than 1.0 µg/L, proving that iron cannot be easily eluted from the resin. The effect of ions naturally present in water on the efficiency of proposed method were studied, four samples of modified water were prepared table 4.8, the different concentration of common inorganic ions (SO42-, NO3-, Cl- and HCO31-) were added to different concentration of As(III) and As(V) species which were related to (CAs(III) = 2.0, 5.0, 10.0 and 25.0 µg/L and CAs(V) = 5.0, 10.0, 25.0 and 50.0 µg/L). The result in table 4.8 confirmed that the arsenic species could be efficiently preconcentrated and determined and removed from water in presence of high concentration of inorganic ions. The results were recovered 96.6 – 100 %. The very high efficiency analysis was obtained. Table 4.8 Results of the proposed methods for determination of total arsenic applied in modified water 4.3.3 Concentration, separation and determination of oAs on HY-AgCl resin To validate the proposed method several samples of deionized water were spiked with different iAs and oAs concentrations to check efficacy of the proposed method for determination of organic arsenic species. Procedure was based on the use of standard samples with addition of differents concentration of iAs and (oAs species in the range of 5.0 µg/L to Standard solutions analyzed Measured Arsenic As content, standard addition Inorganic ions added, mg/L Found in effluent Sample As(III) As(V) SO42- Cl- NO3- HCO3- Total As±σ Recovery (%) 1 2.00 5.00 25.0 25.0 10.0 25.0 7.0±0.8 100.0 2 5.00 10.0 50.0 50.0 25.0 50.0 14.3±1.0 95.3 3 10.0 25.0 75.0 75.0 50.0 75.0 35.0±2.2 100.0 4 25.0 50.0 100.0 50.0 100.0 100.0 72.5±1.5 96.6 68 35 µg/L) to approach concentration of arsenic in natural water. Table 4.9 shows the selected experiments for estimation of the organic arsenic species without any additions of inorganic arsenic species, while the concentration of oAs were lower /higher than concentration of iAs species are presented in table 4.10, which is also related to real water samples. Table 4.11 shows the effect of ions naturally present in water on the determination of oAs. The separation condition for all experiments were: mresin = 10 g; t= 20 °C; pH = 9.0; Q = 1.25 mL/ min, EBV = 12.5 mL, τ = 7.5 min, Vsample = 20 mL, n = 5 The result confirmed that the oAs was not retained on the HY-AgCl resin under the proposed conditions, while the iAs were retained at neutral pH value on the resin. After separation by HY-AgCl only oAs species were present in the water, and can be measured without interference from iAs. Table 4.9 Analytical data of the separation and determination of total oAs species using HY-AgCl resins in standard solutions without adding inorganic arsenic species Standard solutions analyzed Measured, As content standard addition, µg/L Sample oAs iAs Result (µg/L) Recovery (%) DMAs(V) MMAs(V) As(V) As(III) Total oAs oAs±σ oAs 1 5.00 5.00 0.00 0.00 10.0 9.80±0.4 98.0 2 5.00 10.0 0.00 0.00 15.0 15.1±0.96 100.6 3 15.0 5.0 0.00 0.00 20.0 20.54±2.2 102.7 4 10.0 10.0 0.00 0.00 20.0 19.3 ±2.5 96.5 5 20.0 15.0 0.00 0.00 35.0 34.0±0.93 97.1 The results in tables 4.9 and 4.10 confirmed that the organic arsenic species could be efficiently determined in presence of high concentration of iAs. The results were recovered 96.0 – 103.3 % and relative standard deviation was 2.2% - 5.6%. The very high efficiency analysis was obtained. 69 Table 4.10 Analytical data of the separation and determination of oAs species using HY-AgCl resins in standard solutions in the presence of iAs species Standard solutions analyzed Measured, As content standard addition, µg/L Sample oAs iAs Result (µg/L) Recovery (%) DMAs(V) MMAs(V) As(V) As(III) Total oAs oAs±σ oAs 1 5.00 5.00 10.0 5.00 10.0 9.6±0.44 96.0 2 5.00 5.00 20.0 5.00 10.0 10.2±0.68 102.0 3 10.0 5.00 20.0 10.0 15.0 15.5±1.5 103.3 4 10.0 10.0 40.0 20.0 20.0 19.5 ±1.8 97.5 5 20.0 15.0 50.0 30.0 35.0 35.0±0.33 100.0 6 5.00 5.0 100.0 50.0 10.0 9.85±0.55 98.5 7 5.00 0.00 100.0 50.0 5.00 5.0±0.13 100.0 8 0.00 5.00 100.0 50.0 5.0 5.1±0.13 102.0 In analytical chemistry is important to investigate all the evidence that proves efficiency of the proposed method. The modified water samples were prepared by added the common ions in different concentrations to the oAs. The excremental samples and results were presented in the table 4.11 The results obtained very good recoveries were varied in the range 98-104%. The use of Ag-Cl provides accurate results and low detection limit, which gives a very important feature of the method even in the presence of high concentrations of common ions in natural water. Table 4.11 Analytical data of the separation and determination of oAs species using HY-AgCl resins in modified water 4.3.4 Concentration, separation and determination of dimethylarsenate DMAs(V) Standard solutions analyzed Measured, oAs content standard addition, µg/L Inorganic ions added, mg/L Result (µg/L) Recovery (%) Sample MMAs(V) DMAs(V) SO42- Cl- NO3- HCO3- oAs±σ % As 1 5.00 5.00 25.0 25.0 10.0 25.0 10.0±0.3 100.0 2 5.00 5.00 50.0 50.0 25.0 50.0 9.8±0.21 98.0 3 10.0 5.00 75.0 75.0 50.0 75.0 14.5 ±2.5 97.0 4 10.0 10.0 100.0 50.0 100.0 100.0 20.8±1.0 104.0 70 Validation of the proposed method for the water, several samples of deionized water were spiked with different iAs and oAs concentrations to check efficacy of DMAs(V) separation and determination. Testing was based on the use of standard samples spiked with iAs and oAs in the concentration range of 5.0 -100 µg/L to approach concentration of arsenic in natural water. The separation condition were pH = 7.5, mresin = 6.0 g, Q = 1.66 mL/min, EBV= 12.5 mL. The results of samples analysis prepared in deionized water, without and with addition of different concentration of DMAs(V), MMAs(V), As(V) and As(III), are shown in Tables 4.12, 4.13 and 4.14. Table 4.12 Analytical data of the separation and determination of DMAs(V) species using HY-Fe resins in standard solutions As concentration (µg/L) Measured Standard solutions analyzed Result (µg/L) Recovery (%) Sample DMAs(V) MMAs(V) As(V) As(III) DMAs(V)±σ DMAs(V) 1 5.00 0.00 0.00 0.00 4.85±0.4 98.0 2 10.0 0.00 0.00 0.00 10.1±0.66 101.0 3 15.0 0.00 0.00 0.00 15.04±1.4 100.2 4 25.0 0.00 0.00 0.00 25.0±2.20 100.0 5 100 .0 0.00 0.00 0.00 96.0±1.32 96.0 Results in table 4.12 showed that the good recoveries percentages of 96- 101% were obtained and relative standard deviation RSD were 1.1 to 7.5 % for standards solution 1, 2, 3, 4 and 5. The results of analysis of standard samples prepared in deionized water containing different concentrations of DMAs(V) and MMAs(V) are shown in Table 4.13. Good recoveries were found in the samples at DMAs(V) concentration of 5.0, 10, 50 and 100 µg/L, and relative standard deviation RSD were 3.2, 2.6, 4.6 and 2.4%, respectively. The results of analysis of standard samples prepared in deionized water containing different concentrations of DMAs(V) MMAs(V), As(V) and As(III) shown in Table 4.14. The results showed that the Good recoveries of 95.0 – 106 % were obtained with relative standard deviation RSD values of 1.69 to 4.4%. 71 Table 4.13 Analytical data of the separation and determination of DMAs(V) species using HY-Fe resin in standard solutions in the presence of MMAs(V) As concentration (µg/L) Measured Standard solutions analyzed Result (µg/L) Recovery (%) Sample DMAs(V) MMAs(V) DMAs(V) ±σ DMAs(V) 1 5.00 5.00 5.00±0.10 100.0 2 5.00 7.50 5.20±0.08 104.0 3 5.00 10.0 4.60±0.50 92.00 4 5.00 15.0 4.86±0.42 97.20 5 10.0 5.00 10.2±1.20 102.0 6 10.0 10.0 9.00±0.17 90.00 7 10.0 20.0 10.35±1.00 103.50 8 10.0 50.0 9.95±1.40 99.50 9 50.0 50.0 52.73 ± 2.5 104.5 10 100.0 100.0 104.8±2.50 104.8 Table 4.14 Analytical data of the separation and determination of DMAs(V) species using HY-Fe resins in standard solutions containing MMAs(V), As(V) and As(III) Standard solutions analyzed Measured, As content standard addition, µg/L Result (µg/L) Recovery (%) Sample DMAs(V) MMAs(V) As(V) As(III) DMAs(V) ±σ DMAs(V) 1 5.00 5.00 5.00 5.00 4.75±0.06 95.0 2 5.00 5.00 10.0 5.00 5.15±0.06 103.0 3 5.00 5.00 20.0 10.0 5.21±0.06 104.2 4 5.00 10.0 20.0 20.0 4.80±0.20 96.0 5 5.00 5.00 50.0 10.0 4.70±0.12 94.0 6 5.00 10.0 100.0 20.0 5.10±0.05 102.0 7 10.0 10.0 20.0 10.0 10.10±1.2 101.0 8 20.0 40.0 100.0 50.0 18.80±0.21 94.0 9 20.0 50.0 50.0 50.0 21.33±1.6 106.0 10 50.0 20.0 100.0 50.0 52.50±2.2 105.0 The effects of different concentration of ions which are naturally present in water were investigated. The presence of interference ions showed negligible effect on the determination 72 of DMAs(V) as long as concentration of common ions in water reached to 100 mg/l, the results are presented in table 4.15 Table 4.15 Results of the proposed methods for determination of DMAs(V) applied to modified of water The method is simple, easy and achieved good evidence and proof that can use in accuracy determination of very low concentrations of DMAs(V) in different type of liquid sample the method can be used without influence from the other arsenic species 4.4 INTERFERENCES ON DETERMINATION OF iAs AND oAs SPECIES IN WATER 4.4.1 Interference effect on determination of As(III) and As(V) 4.4.1.1 Effect of organic arsenic species In order to elucidate the influence of oAs species for determination of iAs species some experiments were accomplished with methylated arsenic compounds, MMAs(V) and DMAs(V). The presence of oAs compounds in natural waters is the result of anthropogenic activities and natural sources [20]. The methylated arsenic species are weak acids, they are similar to the iAs species with the respect to the relative stabilities of their oxidation states in the environment. Methylated species of As(V) are stable in oxidized system while methylated species of As(III) are unstable and readily oxidized [156]. The presence of both MMAs(V) and DMAs(V) compounds originate from natural sources, and these oAs compounds are found ubiquitously in surface waters. However, oAs compounds appear to contaminate the groundwater as a result of pesticide use [157]. In this part of work only methylated organic species of oAs(V) were tested as the influence to iAs species separation and determination. Standard solutions analyzed Measured As content, standard addition Inorganic ions added, mg/L Found in effluent Sample DMAs(V) MMAs(V) SO42- Cl- NO3- HCO3- Total As±σ Recovery (%) 1 2.50 2.50 25.0 25.0 10.0 25.0 2.5±0.2 100.0 2 5.00 5.00 50.0 50.0 25.0 50.0 4.6±0.32 92.0 3 10.0 5.00 75.0 75.0 50.0 75.0 10.2. ±3 102.0 4 25.0 15.0 100.0 50.0 100.0 100.0 25.8±0.8 103.2 73 b) As(V) As(III) MMAs(V) DMAs(V) 0 50 100 150 200 250 300 0 1000 2000 3000 4000 5000 6000 Volume (mL) A s ( µg /L ) The results obtained with model solutions of iAs and oAs species are presented in Figure 4.10. • The capacities of both resins (SBAE and HY-Fe) for iAs species, in the presence of oAs species, were not significantly decreased (less than 10%). • The SBAE resin was efficient in bonding of both tested oAs species. It was observed that MMAs(V) and DMAs(V) have similar sorption behavior to As(V). Maximum adsorption of both species occurs in neutral and base conditions. The adsorption decreases as pH decreases, which corresponds with the prevailing molecular forms of MMAs(V) and DMAs(V) at lower pH: H2AsO3CH3 ⇌ H+ + HAsO3CH3- ⇌ H+ + AsO3CH32− (4.2) HAsO3(CH3)2 ⇌ H+ + AsO3(CH3)2− (4.3) • The HY-Fe resin was efficient for bonded of all arsenic species except for DMAs(V). It was observed that DMAs(V) was not efficiently sorbed under any of the experimental conditions in this study. The smaller amount of DMAs(V) sorption on HY-Fe resin could be ascribed to the additional methyl group and to its molecular geometry which decreases spatial compatibility with surface sorption sites and HFO particles inside the HY-Fe resin. Fig. 4.10 Breakthrough curves for iAs and oAs species in deionized water on a) SBAE and b) HY-Fe resins, Conditions: CAs(III) = CAs(V) = CMMAs(V) = CDMAs(III) = 5000 µg/L, pH = 7.5, mresin = 6.0g, Q = 1.66 mL/min, EBV = 12.5 mL, n = 3 a) As(V) As(III) DMAs(V) MMAs(V) 0 50 100 150 200 250 300 0 100 200 300 400 500 600 Volume (mL) A s ( µ g/ L) 74 However in natural samples and water supplies for drinking water, which were the object of interest organic compounds were not observed. However, it can be concluded that in the accidental presence of oAs species in water, the capacities of both resins for iAs species will not be significantly decreased and iAs species could be still determined. For the determination of all arsenic species, iAs and oAs, the other more sophisticated procedures should be applied 4.4.1.2 Effect of Inorganic ions Sulfate, chloride, hydrogen-carbonate and phosphate ions in water are considered competing ions. The influence of these ions on separation and determination ofAs(III) and as(V) by ion exchange/sorption efficiency was investigated using a model solution containing these ions in the concentration ranges corresponding to those present in tap water. In some tap water matrices, the concentration of these anions was added to tap water were presented in table 4.16. The concentration of inorganic ions were added to tap water from 10 up to 100 mg/L of sulfate, chloride, phosphate and bicarbonate, but the obtained results indicated no significant influence on the capacity of both examined resins for determination of inorganic arsenic species. It was expected that sulfate ions would noticeably decrease the resin efficiencies. However, in the applied sulfate concentration range, the efficiencies of the analyzed resins towards arsenic remained the same, which is particularly beneficial for application with real drinking water samples. Table 4.16 The concentration (mg/L) of anions in tap water determined by HPLC Test TDS Cl- SO42- F- NO3- Br- Tap water 331.2 15.01 32.92 0.106 3.55 1.074 4.4.2 Interference of inorganic ions on determination of dimethylarsenate DMAs(V) The ions commonly present in the tap water: chloride, sulfate, fluoride and nitrate could have a potential interference in the proposed analytical method. Study of DMAs(V) separation and determination in presence of ions naturally present in drinking water was investigated using drinking water samples spiked by gradual addition of appropriate anion (Cl-, SO42-, F- and NO3-) in a concentration ranging from 10 to 100 mg/L. Ions interference was studied using a 10 µg/L solution of DMAs(V) spiked with different interference ions concentration, at pH 7.0, in order to find out level of noticeable signal depression table 4.17. Presence of interference ions showed negligible effect on the DMAs(V) determination reproducibility as long as total dissolved salts (TDS) were less than 450 mg/L. 75 Table 4.17 Concentration of interfering ions in modified tap water samples determined by HPLC Inorganic ions concentration, µg/L As concentration(µg/L) TDS Cl- SO42- F- NO3- DMAs(V) ±σ Modified Tap water 450 49.93 68.0 0.179 3.44 9.5 ±1.1 Interferences such as chloride and sulfate ions could be tolerated up to concentration of 100.0 mg/L. A severe problem associated with the determination of As by ICP-MS is the interference from a polyatomic species at m/z = 75. The chloride present in the sample reacts with the working gas, resulting in the formation of 40Ar35Cl+ (m/z = 75), the signal which could interfere with those of the As species, leading to inaccurate results. The determination of DMAs(V) in the presence of chloride was accomplished according to the procedure suggested in the literature [148]. Significant signal depression was observed for fluoride and nitrate anion at level of 0.2 and 3.2 mg/L, respectively. These results could not have large influence on the method such as fluoride and nitrate in drinking water are of lower concentration than the detection limit. 4.4.3 Interference of inorganic ions on determination of oAs species Chloride and sulfate ions in a concentration ranging from 10 to 100 mg/L presented no interferences, for arsenic concentration up to 100 µg/L. The resins also provides the advantage of reducing the chloride ion of the sample in the effluent which reduces the problems with polyatomic species 40Ar35Cl+ which could be formed in the plasma and has the same m/z value as naturally occuring 75As isotope. According to this result, the combination of these three resins can be recommended for the separation processes and quantitative determination of iAs and oAs in real water samples. 4.5 EFFECT OF TEMPERATURE ON DETERMINATION OF iAs AND oAs SPECIES It is important to investigate the effect of temperature on the efficiency of the proposed methods. To find out an efficient method of separation and determination of arsenic species, procedure was based on the use of standard samples which were spiked with differents concentration of arsenic species. The separation procedure conducted several experiments at different temperatures 40°C and 80°C. The results obtained in table 4.18, 4.19, 4.20 and 4.21 showed that, at 40°C there is not any effect or change in quantification analysis of arsenic, the results were covering between 102-106 % for all type of resins, which is not different from 76 the selection experiments at room temperature. At 80°C, the results for determination of arsenic species were not improved and were not good, due the (degradation of three type of resins) (Figure 4.11.) As(III) DMAs(V) oAs 0 2 4 6 8 10 12 14 16 18 22° 40° 80° Temperture °C A s ( µg /L) Fig. 4.11 The effect of temperature on determination of arsenic species Table 4.18 Result for determination of As(III) in standard solution by proposed method using SBAE at different temperatures (40°C and 80°C) As content standard addition, µg/L Measured (40°C) µg/L Measured (80°C) µg/L Sample As(III) As(V) As(III)±σ As(III)±σ 1 5.00 5.00 5.10 ±0.22 8.0 ± 0.12 2 10.0 10.0 10.5 ±0.65 14.0± 0.69 3 5.00 50.0 5.30±0.23 35.7±0.94 Table 4.19 Result for determination of iAs species in standard solution by proposed separation method using HY-Fe at different temperatures (40°C and 80°C) As content standard addition, µg/L Measured (40°C) µg/L Measured (80°C) µg/L Sample As(III) As(V) Total iAs±σ Total iAs±σ 1 5.00 5.00 10..85± 0.13 2.70± 0.6 2 10.0 10.0 19.90± 0.32 4.4± 0.16 3 5.00 50.0 55.20±0.23 26.0±2.33 77 Table 4.20 Result for determination of oAs species in standard solution by proposed method using HY-AgCl at different temperatures (40°C and 80°C) As content standard addition, µg/L Measured(40°C) µg/L Measured (80°C) µg/L Sample MMAs(V) DMAs(V) As(III) As(V) oAs±σ oAs±σ 1 5.00 5.00 5.00 5.00 10.0± 0.8 15.7± 0.06 2 5.00 5.00 10.0 10.0 10.1± 0.42 15.0± 0.88 3 5.00 5.00 10.0 20.0 9.80± 0.6 28.0±1.12 Table 4.21 Result for determination of DMAs(V) in standard solution by proposed method using HY-Fe at different temperatures (40°C and 80°C) As content standard addition, µg/L Measured, (40°C) µg/L Measured, (80°C) µg/L Sample MMAs(V) DMAs(V) As(III) As(V) DMAs(V) ±σ DMAs(V) ±σ 1 5.00 5.00 5.00 5.00 5.0±0.6 13.7± 0.61 2 5.00 10.0 10.0 50.0 10.3±0.22 66.0± 1.23 3 10.0 25.0 10.0 50.0 24.55±1.1 76.0± 3.2 4.6 ANALYTICAL PROPERTIES OF NEW PROCEDURES FOR PRECONCENTRATI- -ON, SEPARATION AND DETERMINATION OF As(III), As(V), MMAs(V), DMAs(V) SPECIES IN STANDARD SOLUTION The difference in retaining different arsenic species by three types of resins enables to propose a selective separation method before the measurements of concentration of each arsenic species. The procedure for separation and determination of four arsenic species in water was peformed in two steps. First step is always the measurement of total inorganic arsenic in samples (CAs). It was done directly without adding any reagent (only standard acidification of the sample with 5.0% HNO3 and filtration) by ICP−MS. The second step comprehends a procedure for separation and determination of arsenic species in water. The scheme for selective separation with 78 subsequent quantitative measurement of the arsenic species by ICP−MS technique is shown in Figure. 4.12 Separation columns were prepared (diameter of 2.0cm) by packing with three investigated resins (m=6.0 g), and washing with deionized water. Sample of water was adjusted at adequate pH value by using 0.01M HNO3 or 0.01M NaOH, and passed through the column at flow rate of 1.25−1.66 mL/min. The total volume of the effluent was 100 mL and it was used, with pH adjustment, for injection directly into ICP−MS. The concentrations of each species was measured directly or calculated by the difference between the total arsenic concentration determined in first step and concentration of species determined in second step. The sampling was performed according to a simple sampling procedure without addition of any reagent for stabilization. Arsenic species in water were stable under neutral conditions for a period of four months if they are placed in polypropylene bottles in a refrigerator. Before all ICP−MS measurements, the samples were acidified with 5.0% HNO3. Concentration of As(III) was measured directly in the effluent of SBAE resin. Concentration of DMAs(V) was measured directly in the effluent of HY−Fe resin. Concentration of oAs [MMAs(V) and DMAs(V)] was measured directly in the effluent of HY−AgCl resin. The concentration of As(V) and MMAs(V) were calculated from: CMMAs(V) = CoAs − CDMAs(V) (4.4) CAs(V) = CAs − CAs(III) − CoAs (4.5) Where: CAs(III) is concentration of As(III) in µg/L, CAs(V) is concentration of As(V) in µg/L, CoAs is concentration of organic species of arsenic in µg/L, CMMAs(V) is concentration of MMAs(V) in µg/L, and CDMAs(V) is concentration of DMAs(V) in µg/L. The developed method was applied for determination of iAs and oAs species in different water samples. In order to be concise the results of wide investigations by proposed procedures with standard solutions are presented in table 4.22. 79 Fig. 4.12 Scheme for selective separation and determination of the arsenic species in water using SBAE, HY-Fe and HY-AgCl resins Standard arsenic solutions were prepared by standard procedure. The concentrations investigated were very low, closed to MPC in drinking water (10 µg/L). Results presented in table 4.22 confirmed that As(III) as a nonionic species was not retained on the SBAE resin under proposed conditions, whereas As(V) and oAs, which are present as anionic species, are retained on resin. After separation by HY−Fe, only DMAs(V) species were present in the water, while after separation by HY−AgCl resin iAs species were not present in the water, only oAs was confirmed by ICP−MS measurements and calculations. Good recoveries were found in the samples that contained traces and low concentrations of arsenic up to 5.0 µg/L of DMAs(V) and MMAs(V). The results showed that DMAs(V) and MMAs(V) exist after the separation process and they are not bonded with the HY−AgCl resin at pH less than 9.0, while As(V) and As(III) were bonded with HY−AgCl resin. The RSD for 80 organic arsenic for total concentration of 10, 15, 20, 25 µg/L was between 1.3−5.1%. The recovery and reproducibility of laboratory blank and spiked samples were good. Table 4.22 Results of the proposed separation procedure by SBAE, HY-Fe and HY-AgCl resin applied for the standard arsenic solutions. Separation conditions: mresin=6.0 g, temp.=20 oC, Q=1.25-1.66 mL/min, EBV=12.5 mL, τ=7.5 min, Vsample=100 mL, n=5 4.7 ANALYTICAL PROPERTIES OF NEW PROCEDURES FOR PRECONCENTRATI- -ON, SEPARATION AND DETERMINATION OF ARSENIC SPECIES IN REAL DRINKING WATER AND RIVER WATER After evaluating the main features of the proposed speciation procedure, its application to the analysis of tap water and drinking water samples from the Vojvodina region, known as region in which underground waters have an appreciable arsenic content, was performed. The samples were analyzed without any previous stabilization or preservation. The method of standard addition was applied; each sample was analyzed twice, with and without spiking. Standard solutions of both arsenic species were added as presented in table 4.23, 4.24 and As concentration, µg/L Standard solutions analyzed Found in effluent Sample As(III) As(V) MMAs(V) DMAs(V) Total As As±σ %As SBAE; pH=7.0 1 0.00 5.0 5.00 5.00 15.0 <0.030 / 2 5.00 5.0 5.00 5.00 20.0 5.20±0.25 104 3 5.00 10.0 5.00 5.00 25.0 4.80±0.18 96.0 4 10.0 5.0 5.00 5.00 25.0 10.62±0.24 105 5 10.0 10.0 10,0 10.0 40.0 9.50±0.35 95.0 6 5.00 25.0 5.00 5.00 40.0 5.05±0.22 101.0 HY-Fe; pH=7.0 1 5.00 5.00 5.00 0.00 15.0 <0.030 / 2 5.00 5.00 5.00 5.00 20.0 4.75±0.80 95.0 3 5.00 5.00 5.00 10.0 25.0 10.64±0.41 106 4 10.0 5.00 5.00 5.00 25.0 5.06±0.12 100.0 5 10.0 10.0 10,0 10.0 40.0 9.60±0.43 96.0 6 25.0 25.0 10.0 5.00 65.0 5.05±0.11 101.0 HY-AgCl, pH=9.0 1 5.00 5.00 0.0 0.00 10.0 <0.030 / 2 5.00 5.00 5.0 5.00 20.0 9.77±0.27 97.7 3 5.00 5.00 5.0 10.0 25.0 15.60±0.54 104 4 10.0 5.00 5.0 5.00 25.0 10.53±0.44 105 5 10.0 10.0 10,0 10.0 40.0 18.75±0.95 93.7 6 1.00 1.00 10.0 15.0 27.0 23.00±2.00 92.0 7 5.00 5.00 10.0 15.0 35.0 25.0±1.21 100.0 81 4.25. The standard addition method is useful because some unknown variations of the matrix can be prevented, and it was suggested in some studies [146,158]. Table 4.23 Results of arsenic analysis of real water samples by the proposed separation method using SBAE resin, n = 3 a The values were previously determined by HG-AAS 4.7.1 Application of proposed methods for determination of As(III) and As(V) in real drinking water and river water All analyzed samples were from the Vojvodina region. The determination of the arsenic in the samples presented in table 4.23, showed different levels of arsenic; sample #1 had about 1.0 µg/L, but the other samples contained higher amounts. It is notable that the mass balance for the total arsenic was the sum of the two arsenic species found by the AAS-HG technique. Measured As content a Standard addition (µg/L) Result, (µg/L) Recovery (%) Sample As(III) As(V) As(III)±σ As(V)±σ As(III) As(V) Tap water # 1 Added <0.02 1.00 0.55 1.00 1.03±0.06 1.59± 0.08 103.0 102.5 Tap water # 2 Added <0.02 5.00 0.55 5.00 5.20±0.36 5.45±0.2 104.0 98.0 Tap water # 3 Added <0.02 5.00 0.55 10.0 5.14±0.1 10.95 ± 0.09 102.8 103.7 Modified tap water # 1 Added <0.02 1.00 0.55 1.00 0.98±0.09 1.50± 0.02 98.0 97.0 Modified tap water # 2 Added <0.02 5.00 0.55 5.00 5.05±0.2 4.59± 0.05 101.0 92.0 Well #1, Zrenjanin added 145.0 10.0 70.0 10.0 150.5±2.6 81.6± 1.09 97.1 102.0 Well #2, Zrenjanin added 15.0 10.0 100.0 10.0 25.25±2.0 105.65± 1.15 101.0 96.1 Lake Palic added 22.0 10.0 75.0 10.0 30.05±2.06 86.2± 1.09 94.0 101.4 Well#1, Obrovac added 14.2 10.0 70.0 10.0 23.08±2.30 82.0±1.10 95.4 102.5 82 Good recoveries were found in the samples that contained traces and low concentration of arsenic species. Smaller recoveries for As(III) species in some samples could be due to the possible oxidization of As(III) to As(V). The recovery for As(V) was always higher than for As(III) species. The recovery and reproducibility of laboratory blank and spiked samples were good. No interference effects were observed in the studied natural water samples. With this simple procedure, analysts obtain a good insight into status of arsenic species in water samples. This represents a great improvement compared with direct ICP-MS measurements, which gives only data of the total arsenic concentration. This method can be recommended for speciation analysis when appropriate equipment for highly sophisticated coupled techniques are not available. The proposed procedure can be adapted for on site collection or separation of As(III) and As(V) prior to their determination in laboratories. 4.7.2 Application of proposed method for determination of organic arsenic oAs species in real drinking water The results of the arsenic species analysis of real water samples are presented in table 4.24. It is noticeable that the mass balance for the total arsenic was the sum of the four arsenic species. The results indicate different levels of arsenic; tap water had less than 0.52 µg/L, but other samples contained higher amounts of arsenic. Good recoveries were found in the samples that contained traces and low concentration of arsenic up to 5.0µg/L. The presence of oAs compounds was observed only in one sample, it was wastewater sample, and the presence of oAs is the result of anthropogenic activities. oAs is very rarely present in natural waters [159]. The recovery and reproducibility of laboratory blank and spiked samples were good. No interference effects were observed in the water samples analysis. With this simple procedure, analysts obtain a good insight into status of organic arsenic species in water samples. This represents a great improvement compared with direct ICP−MS measurements, which gives only data of the total arsenic concentration. This method can be recommended for speciation analysis when appropriate equipment for highly sophisticated coupled technique is not available. Table 4.24 Results of arsenic speciation analysis of real water samples by proposed separation method using SBAE, HY-Fe and HY-AgCl resins 83 Arsenic concentration, µg/L Arsenic species Sample As(III) As(V) MMAs(V) DMAs(V) Tap water ±σ <0.030 0.52±0.06 <0.030 <0.030 Added 5.00 5.00 5.00 5.00 Measured ±σ 4.55±0.15 5.34±0.25 4.63±0.28 4.42±0.20 Recovery % 91.0 96.0 92.4 88.4 Lake water 23.40±1.05 72.00±2.95 <0.030 <0.030 Added 10.00 10.00 5.00 5.00 Measured 33.90±1.12 80.10±3.16 4.80±0.50 4.62±0.83 Recovery 101.5 97.6 96.0 92.4 Well water ±σ 15.20±0.78 55.00±1.18 <0.030 <0.030 Added 10.00 10.00 5.00 5.00 Measured ±σ 25.60±2.03 65.80±2.98 4.80±0.05 4.58±0.09 Recovery 102.4 101.2 96.0 91.6 Wastewater ±σ 98.30±3.75 110.5±5.15 0.58±0.030 <0.030 Added 10.00 10.00 5.00 5.00 Measured ±σ 110.7±4.05 122.5±6.43 4.54±0.09 4.76±0.06 Recovery 102.2 101.6 90.8 95.2 4.7.3 Application of proposed method for determination of dimethylarsenate DMAs(V) in drinking water The proposed method has been applied to drinking water samples in order to separate and determine DMAs(V). In table 4.25 are presented the results of DMAs(V) determination in drinking water samples spiked with different concentrations of arsenic species. The standard addition method is useful because some unknown variations of the matrix can be prevented and this was suggested in some studies [146,158] because no water samples with known concentrations of various arsenic species were available, the accuracy of the analytical results was evaluated by recovery studies. The table 4.25 illustrated that the recovery and 84 reproducibility of tap water samples and modified water were good, with RSD values of 3.9 to 5.4%. Table 4.25 Analytical data of the determination of DMAs(V) species using HY-Fe and SBAE resins in tap water and Modified tap water containing MMAs(V), As(V) and As(III) Standard solutions analyzed Measured Sample As content standard addition, µg/L (µg/L) Recovery (%) DMAs(V) MMAs(V) As(V) As(III) DMAs(V) ±σ DMAs(V) Tap water 1 5.00 5.00 5.00 5.00 4.55±0.05 91.0 Tap water 2 5.00 5.00 10.0 5.00 5.15±0.2 103 Tap water 3 10.0 10.0 100 10.0 9.95±1.1 99.5 Tap water 4 10.0 50.0 100 50.0 10.0±0.2 100.0 Tap water 5 50.0 50.0 100 50.0 48.1± 1.0 96.2 Modif. tap water # 1 50.0 50.0 100 50.0 53.3±2.8 106.6 Modif. tap water # 1 5.00 5.00 50.0 10.0 5.05 ±1.0 101.0 Modif. tap water # 3 10.0 10.0 50.0 10.0 10.11±0.9 101.1 Modif. tap water # 4 5.00 5.00 5.00 5.00 4.85±0.5 97.0 V CONCLUSION 85 V CONCLUSION The aim of the thesis was the development and application of hybrid sorbents for determination of arsenic species and selective removal of arsenic from water. Water soluble arsenic species in natural water are inorganic (iAs) species as arsenite, As(III) and arsenate, As(V). As a result of anthropogenic pollution in water can be present organic (oAs) species as monomethilarsenic acid, MMAs(V) and dimethylarsenic acid, DMAs(V). Each method developed for iAs species should consider and solve oAs species as interferences for the iAs determinations. In the frame of these tasks efficiency of three types of resins were investigated: a strong base anion exchange (SBAE) resin and two hybrid (HY) resins, HY-Fe which integrates sorption activity of hydrated iron oxides (HFO) with the anion exchange function and HY-AgCl which integrates effects of chemical reaction the anion exchange function. Two systems were employed: a batch and a fixed bed flow system. The selective bonding of arsenic species on three types of resins makes possible the development of the procedure for measuring, and calculation of all arsenic species in water. In order to determine capacity of resins the preliminary investigations were performed in batch system and fixed bed flow system. Resin capacities were calculated according to breakthrough points in a fixed bed flow system which is the first step in designing of solid phase extraction (SPE) module for arsenic speciation separation and determination. The main achievement of thesis is that three methods for arsenic species determination were developed. A method for preconcentration, separation and determination of iAs species in natural and drinking water is the first method. This method is based on the selectivity of two types of resins, the strong base anion exchange, SBAE, and the hybrid resin, HY. HY resins integrates the anion exchange function with sorption and chemisorption. The HY-Fe integrates the anion exchange function with sorption on hydrated iron oxides (HFO). The separation of As(III) and As(V) species on SBAE resin was accomplished by adjusting the acidity of water samples to a pH less than 8.00; ionic forms of As(III) were bonded while molecular forms of 86 As(V) were retained in water. The preconcentration of all iAs species was accomplished with HY-Fe resin. A method for separation and determination of iAs and oAs species is a second method. This method is based on the application of three types of resins, an anion-exchange, SBAE and two hybrid resins: HY-Fe and HY-AgCl. The SBAE resin was convenient for the separation of As(III) from As(V) and oAs species. The concentration of As(III) can be measured directly in the effluent of the SBAE resin, while anionic forms of other arsenic species were retained on SBAE resin. The HY-Fe resin was convenient for the separation of DMAs(V) from all other arsenic species, which were retained on the HY-Fe resin that has a high sorption capacity for the arsenic species, 9000 µg/g. The concentration of DMAs(V) can be measured directly in the effluent of the HY-Fe. A new hybrid resin, the HY-AgCl resin, was synthesized in our lab and it was effective for iAs and oAs analytical separation. The concentration of oAs was measured directly in the effluent of the HY-AgCl. Concentrations of As(V) and MMAs(V) were calculated. The third method is a simple and efficient method for separation and determination of dimethylarsenate DMAs(V). Two resins, SBAE and HY-Fe were tested. By simple adjusting pH value of water at 7.0, DMAs(V) passed through the HY-Fe column without any changes, while all other arsenic species (inorganic arsenic and monomethyl-arsenate, MMAs(V)) were quantitatively bonded on HY-Fe resin. The resin capacity was calculated according to the breakthrough points in a fixed bed flow system. At pH 7.00 the HY-Fe resins bonded more than 4150 µg/g of As(III), 3500 µg/g of As(V) and 1500 µg/g of MMAs(V). Arsenic adsorption behavior in the presence of impurities showed tolerance with the respect to potential interference of anions commonly found in natural water. DMAs(V) was determined in the effluent by ICP-MS. The detection limit was 0.03 µg/L and relative standard deviation (RSD) was between 1.1-7.5 %. The separation and preconcentration procedures were well coordinated with the ICP-MS technique for a sensitive determination of the total As concentration and iAs and oAs species at low µg/L. Measurements with certified reference materials proved that the measurements of arsenic species concentrations in model solutions and real samples were in agreement with the certified values. 87 With the proposed separation and preconcentration procedures, satisfactory results of the analysis of As species in water were obtained. Methods could be applied routinely for monitoring arsenic levels in various water samples: fresh natural, drinking water and wastewater. The proposed procedures showed themselves to be accurate, precise and time efficient, as just a very simple sample treatment is required. Speciation analysis can be realized through implementation of adequate non-chromatographic separation procedures, standard methods and highly sophisticated equipment for detection. FUTURE WORK The work presented in the thesis provides a good foundation for many studies involving sorbents for selective bonding of arsenic species. Past works have shown that iAs species can be separated simply by acidification of water. It would be interesting for future studies to investigate selective sorbents for total removal of all arsenic species and some new sorbent for specific removal of only one arsenic species without preparing the pH value of water. It would be very interesting to develop the procedure for encapsulating the sorbent particles in order to reuse sorbent. Open question is how to dispose sorbent saturated by arsenic species. Arsenic studies would be an excellent way to investigate the question of integrated process for removal of arsenic. Furthermore, since aqueous arsenic concentrations are so low after reaction with sorbent, it is critical to establish a low method detection limit to obtain a high degree of certainty in experimental results for all arsenic species. VI. REFERENCES 88 VI. REFERENCES [1] S. Caroli, Element speciation in bioinorganic chemistry, chemical analysis: A series of monographs on analytical chemistry and Its applications, v 135 (1996). [2] Arsenic in drinking water, National academies press, (1999). [3] O.S. Thirunavukkarasu, T. Viraraghavan, K.S. Subramanian, S. Tanjore, Urban Water. 4 (2002) 415-421. [4] www.speciation.net/Database/Links/EPA-Arsenic-Speciation-Methods [5] K. J. Irgolic, Appl. Organomet. Chem. 2 (1988) 303-307. [6] F. T. Henry, T. M. Thorpe, Anal. Chem. 52 (1980) 80-83. [7] B. Petrusevski, S. Sharma, J.C. Schippers, K. Shordt, IRC International water and sanitation centre thematic overview paper 17 (2007). [8] P.L. Smedley, D.G. Kinniburgh, Appl. Geochem. 17 (2002) 517-568. [9] P. Pohl, B. Prusisz, Trends Anal. Chem. 23 (2004) 63-69. [10] R.T. Gettar, R.N. Garavaglia, E.A. Gautier, D.A. Batistoni, J. Chromatogr. A, 884 (2000) 211–221. [11] V. K. Saxena, S. Kumar, V. S. Singh, Curr. Sci. 86, 2, 25 (2004) 281-284. [12] A. Maiti, S. DasGupta, J. K. Basu, Si. De, Indus. Eng. Chem. Res, 47 (2008) 1620-1629. [13] K.A. Hudson-Edwards, S.L. Houghton, A. Osborn, Trends Anal. Chem. 23 (2004) 745-752. [14] N. B. Issa, V. N. Rajaković-Ognjanović, Aleksandar D. Marinković, Lj. V. Rajaković, Anal. Chim. Acta 706 (2011) 191-198. [15] Y. Odanaks, N.Tsuchiya, O. Matano, S. Goto, Anal. Chem. 55 (1983) 929-932. [16] J. L. Gomez Ariza, E. Norales, D. Sanchez-Rodas, I. Giraldez, Trends Ana.Chem. 19 (2000) 200-209. [17] N. B. Issa, V. N. Rajaković-Ognjanović, B. M. Jovanović, Lj. V. Rajaković, Anal. Chim. Acta 673 (2010) 185-193. [18] N. B. Issa, Aleksandar D. Marinković, Lj. V. Rajaković, J. Serb. Chem. Soc. 77 (6) (2012) 775–788 [19] M. B. Amran, F. Lagarde, M. J. F. Leroy, Microchem. Act. 127 (1997) 195-202 [20] K. Jitmanee, M. Oshima, S. Motomizu, Talanta, 66 (2005) 529–533. [21] M. Chausseau, C. Roussel, N. Gilon, J. M. Mermet, Fresen. J. Anal. Chem. 336 (2000) 476- 480 [22] P. Schramel, Li-Qiang Xu, Fresen. J. Anal. Chem. 340 (1991) 41-47 [23] E. H. Evans, J. J. Giglio, J. Anal. Atom. Spectrom. 8 (1993) 1-8. [24] Agilent Technologies, Inc. 2004 (www.agilent.com/chem/icpms) [25] Lj. V. Rajakovic, Sep. Sci. Technol. 27 (11) (1992) 1423-1433. 89 [26] Lj.V. Rajaković, M. Mitrović, Environ. Pollut. 75 (1992) 279-287. [27] A. Pillai, G. Sunita, V.K. Gupta, Anal. Chim. Acta. 408 (2000) 111–115. [28] P. Niedzielski, M. Siepak, Poli, J. Environ. Stud. 12 (6) (2003) 653-667 [29] H. D. Revanasiddappa, B. P. Dayananda, T. N. K. Kumar, Environ. Chem. Lett. 5 (2007) 151- 155. [30] S. Kundu, S. K. Ghosh, M. Mandal, T. Pal, A. Pal, Talanta, 58 (2002) 935-94 [31] R.K. Dhar, Y. Zheng, J. Rubenstone, A. van Geen, Anal. Chim. Acta. 526 (2004) 203–209 [32] K. Morita, E. Kaneko, Anal. Sci. 22 (2006) 1085-1089. [33] M. A. Desesa, L. B. Rogers, Anal. Chem. 26 (1954) 1381-1383 [34] Lj.V. Rajaković, M. Mitrović, S. Stevanović, S. Dimitrijević, J. Serb. Chem. Soc. 58 (2) (1993) 131-143. [35] S. S. Sandhu, P. Nelson, Anal.Chem. 50 (2) (1978) 322-325. [36] A. Chatterjee, D. Das, B. K. Mandal, T. R. Chowdhury, G. Samata, D. Chakraborti, Analyst, 120 (1995) 643-650. [37] B. Narayana, T. Cherian, M. Mathew, C. Pasha, Indian. J. Chem. Technol. 13 (2006) 36-40. [38] P. K. Dasgupta, H. Huang, G. Zhang, G. P. Cobb, Talanta, 58 (2002)153–164 [39] T. Rupasinghe, T. J.Cardwell, R. W. Cattrall,; M. D. Luque de Castro, S. D. Kolev, Anal. Chim. Acta, 445 (2001) 229-238. [40] T. Rupasinghe, T. J. Cardwell, R. W. Cattrall, I. D. Potter, S. D. Kolev, Anal. Chim. Acta, 510 (2004) 225-230. [41] K. Toda, T. Ohba, Chem. Lett. 34 (2005) 176-177. [42] R. S. Braman, D. L. Johnson, C. C. Foreback, J. M. Ammons, J. L. Bricker, Anal. Chem. 49 (1977) 621-625. [43] A. Shaikh, D. E. Tallman, Anal. Chim. Acta 98 (1978) 251-259. [44] M. Borho, P. Wilderer, Aqua, 46 (1997) 138-143. [45] D. Razo, M. Luz, M. Styblo, W. R. Cullen, D. J. Thomas, Toxicol. Appl. Pharm. 174 (2001) 282-293. [46] K. Toda, T. Ohba, M. Takaki, S. Karthikeyan, S. Hirata, P. K Dasgupta, Anal. Chem. 77 (2005) 4765- 4773. [47] H. Li, R. B. Smart, Anal. Chim. Acta. 325 (1996) 25-32. [48] W. Holak, Anal. Chem. 52 (1980) 2189-2192. [49] P. Salaun, B. Planer-Friedrich, C. M.G. van den Berg, Anal. Chim. Acta. 585 (2007) 312–322. [50] J. R .Pretty, E. A. Blubaugh, J. A. Caruso, Anal. Chem. 65 (1993) 3396-3403. [51] R.S. Sadana, Anal. Chem. 55 (1983) 304-307. [52] G, Henze, W. Wagner, S. Sander, Fresen. J. Anal. Chem. 358 (1997) 741-744. [53] G. Forsberg, J.W. O’Laughlin, R.G. Megargle, S.R. Koirtyihann, Anal. Chem. 47 (1975) 1586-1592. 90 [54] K. Gibbon-Walsh, P. Salaün, C. M.G. van den Berg, Anal. Chim. Acta. 662 (2010) 1–8. [55] A. Profumo, D. Merli, M. Pesavento, Anal. Chim. Acta. 539 (2005) 245–250. [56] D. M. Templeton, F. Ariese, R. Cornelis, L. G. Danielsson, H. P. Van Leeuwen, R. Lobinski, Pure. Appl. Chem. 72 (2000) 1453-1470. [57] S. Ahuja. Chromatography and Separation science, Elsevier Science, volume 4 (2003) [58] W. Holak, Anal. Chem. 41 (1969) 1712-1713. [59] R. S. Braman, L. L. Justen, C. C. Foreback, Anal. Chem. 44 (1972) 2195-2199. [60] P. Pohl, Trends Anal. Chem. 23 (2004) 87-101. [61] H. Lauri, J. Lajunen, Spectrochemical Analysis by Atomic Absorption and Emission, Royal Society of Chemistry, Oulu, November (1991) [62] R.G. Godden, D.R. Thomerson, Analyst, 1257 (1980) 1137-1156. [63] APHA, AWWA, WEF, Standard Methods for the Examination of Water and Wastewater, 19th edition, 1995, Denver [64] V.L.Vukašinović-Pešić, Lj.V. Rajaković, Energy Sources Part A: Recovery, Utilization, and Environmental Effects 31 (2009) 1583-1589. [65] Z. Zhua, J. Liub, S. Zhanga, X. Nab, X. Zhanga, Anal. Chim. Acta. 607 ( 2008 ) 136–141. [66] http://www.shsu.edu/~chm_tgc/primers/pdf/HGAAS.pdf [67] R. Schaeffer, C. Soeroes, I. Ipolyi, Pe. Fodor, N. S. Thomaidis, Anal. Chim. Acta. 547 (2005) 109–118. [68] J.G. Hering, P. Chen, J.A. Wilkie, M. Elimelech, S. Liang, J. Am. Water Works Assoc. 88 (1996) 155-167. [69] F.J. Schmidt, J.L. Royer, Anal. Lett. 6 (1) (1973) 17-23. [70] L.O. Leal, R. Forteza, V. Cerda, Talanta, 69 (2006) 500–508. [71] G. Samanta, D. A. Clifford, Environ. Sci. Technol. 39 (2005) 8877-8882. [72] P. K. Pandey, S. Yadav, S. Nair, M. Pandey, Curr. Sci. 86 (2004) 1426-1432. [73] E. Gwendy, M. Hall, J. C. Pelchat, G. J. Gauthier, Anal. Atom. Spectrom. 14 (1999) 205-213. [74] X. Yan, X. Yin, X. He, Y.Jiang, Anal. Chem. 74 (2002) 2162-2166. [75] E. Bolea, F. Laborda, M. A. Belarra, J. R. Castillo, Spectrochim. Acta, B, 56 (2001) 2347- 2360. [76] F. D. Pierce, H. R. Brown, Anal. Chem. 48 (1976) 693-695. [77] A. Meyer, Ch. Hofer, G. Toelg, S. Raptis, G. Knapp, Fresen. Anal. Chem. 296 (1979) 337- 344. [78] B. Welz, M. Melcher, Analyst, 109 (1984) 569-572. [79] A. E. Smith, Analyst, 100 (1975) 300-306. [80] Y. Yano, T. Miyama, A. ITo, T. Yasuda, Anal. Sci. 16 (2000) 939-943. [81] S. Nielsen, E. H. Hansen, Anal. Chim. Acta. 343 (1997) 5-17. [82] CJ. Hsieh, CH. Yen, Ms. Kuo, Anal, Sci. 13 (1999) 669-673. 91 [83] M. Tswett (1872-1920) Leslie S. Ettre, Dept of Chemical Engineering, Yale University, New Haven, Connecticut, USA. [84] http://www.waters.com/waters/nav.htm [85] S. Simon, H. Tran, F. Pannier, M.Potin-Gautier, J. chromatogr. A, 1024 (2004) 105-113. [86] M. Pantsar-Kallio, P. K. G. Manninen, J. Chromatogr. A, 779 (1997) 139-146. [87] S. Yalçin , XC. Le, J. Environ. Monitor. 3 (2001) 81-85. [88] H. F. Walton, R. D. Rocklin. CRC press (1990) [89] O. Samuelson, ion Exchange Separations in Analytical Chemistry, Wiley, New York, London (1963) [90] D. Chen, C. Huang, M. He, B.Hu, J. of Hazard. Mater. 164 (2009) 1146–1151. [91] A.T. Calzada, M.C. Villa-Lojo, E. Beceiro-Gonzaelez, E. Alonso-Rodrieguez, D. Prada- Rodrieguez, Trends Anal. Chem. 17 (1998) 167-175. [92] J. Koh,, Y. Kwon, Y-N. Pak, Microchem. J. 80 (2005) 195-199. [93] A.N. Anthemidis, E. K. Martavaltzoglou, Anal. Chim. Acta. 573–574 (2006) 413–418. [94] Y. Zhang, W. Wang, L. Li, Y. Huang, J. Cao, Talanta, 80 (2010) 1907–1912. [95] S. Chen, X. Zhan, D. Lu, C. Liu, L. Zhu, Anal. Chim. Acta. 634 (2009) 192–196. [96] H. Wu, X. Wang, B. Liu, Y. Liu, S. Li, J. Lu, J. Tian, W. Zhao, Z. Yang, Spectrochim. Acta B. 66 (2011) 74–80. [97] B. Staniszewski, P. Freimann, Spectrochim. Acta. B, 63 (2008) 1333–1337. [98] L. Zhang, Y. Morita, A. Sakuragawa, A. Isozaki, Talanta, 72 (2007) 723-729. [99] C. Yu, Q. Cai, Z Guo, Z. Yang, S.B. Khoo, Spectrochim. Acta B, 58 (2003) 1335-1349. [100] C. Xiong, M. He, B. Hu, Talanta, 76 (2008) 772–779. [101] F. Shemirani, M. Baghdadi, M. Ramezani, Talanta, 65 (2005) 882–887. [102] I. M. M. Rahman, Z.A Begum, M. Nakano, Y. Furusho, T. Maki, H. Hasegawa, Chemosphere 82 (2011) 549-556. [103] I. Martín, M. A. López-Gonzálvez, M. Gómez, C. Cámara, M. A. Palacios, J. Chromatogr. B, 7 (1995) 101-109. [104] S. Hirata, H. Toshimitsu, M. Aihara, Anal. Scie. 22 (2006) 39-43. [105] Routine Analysis of Toxic Arsenic Species in Urine Using Agilent HPLC with 7500 Series ICP-MS Agilent Technologies The application notebook (2006) [106] S. Londesborough, J. Mattusch, R. Wennrich, Fresen. J. Anal. Chem. 363 5-6, 577-581, DOI: 10.1007/s002160051251 [107] C. B, Hymer, J. A. Caruso, J. Chromatogr. A, 1045 (2004) 1-13. [108] K.A. Francesconi, D. Kuehnelt, Analyst, 129 (2004) 373-395. [109] Z. Chen , K.F. Akter, M. M Rahman , R Naidu, J. Sep. Sci. 17, 267 (2006), 1-6. [110] L. Orero Iserte, A.F. Roig-Navarro, F. Hernandez, Anal. Chim. Acta. 527 (2004) 97–104. 92 [111] B Do, P Alet, D Pradeau, J Poupon, M Guilley–Gaillot, F Guyon, J. Chromatogr. B, 740, (2000) 179-186 [112] J. T. Van Elteren, Z. J. Slejkovee, J. Chromatogr. A, 789 (1997) 339-348. [113] J.Szkoda, J. Żmudski, A. Grzebalska, Bull Vet Inst Pulawy, 50 (2006) 269-272. [114] S.L. Chen, S.J. Yeh, M.H. Yang, T. H. Lin, Biol. Trace Elem. Res. 48 (1995) 263-274. [115] L.S. Milstein, A. Essader, E. D. Pellizari, R.A. Fernando, J. H. Raymer, K E.Levine, O. Akinbo, Environ. Health. Persp. 111 (2003), 293-296. [116] V.L.Vukašinović-Pešić, N.Z.Blagojević, Lj.V.Rajaković, Instrum. Sci. Technol., 37 (4) (2009) 482 498. [117] B. Do, S. Robinet, D. Pradeau, F. Guyon, J. Chromatogr. A, 918 (2001) 87-98. [118] T. Guérin, A. Astruc, M. Astruc, J. Chromatogr. Sci. 35 (1997) 213-219 [119] A. F. Roig-Navarro, Y. Martinez-Bravo, F.J. Lopez, F .Hernandez, J. Chromatogr A, 912 (2001) 319-327. [120] R. Xie, W. Johnson, S. Spayd, G. S. Hall, B. Buckley, Anal. Chim. Acta. 578 (2006) 186-194. [121] E. Vassileva, A. Becker, J.A.C. Broekaert, Anal. Chim. Acta. 441 (2001) 135–146. [122] I. Pizarro, M. Gómez, C. Cámara, M.A. Palacios, Anal. Chim. Acta. 495 (2003) 85–98. [123] C. Demesmay, M .Olle, M. Porthault, Fres. J. Anal. Chem. 348 (1994) 205-210. [124] M. Morita, T. Uehiro, K.Fuwa, Anal. Chem. 53 (1981) 1806-1808. [125] Do Q. Trung, C. X. ANH, N. X. Trung, Y. Yuta, F. Masanori, T. Minoru, Anal. Sci. 17 (2001) 1219-1222 [126] M. A. Lopez, M. M.Gomez, M. A. Palacios, C. Camara, Fresen. J. Anal. Chem. 346 (1993) 643-647. [127] N.M. M. Coelho, C. Parrill, M.L. Cervera, A. Pastor, M. de la Guardia, Anal. Chim. Acta. 482 (2003) 73–80. [128] V.D. Nguyen, H. Neumeister, G. Subklew, Frens. J. Anal. Chem. 363 (1999) 783-788. [129] J. Frank, M. Krachler, W. Shotyk, Anal. Chim. Acta. 530 (2005) 307–316 [130] K. Baba, T. Arao, Y. Maejima, E. Watanabe, H. Eun, M. Ishizaka, Anal. Chem. 80 (2008) 5768–5775. [131] S. Ketavarapu, S. Yathavakilla, M. Fricke, P. A. Creed, D. T. Heitkemper, N. V. Shockey, C. Schwegel, J. A. Caruso, J. T. Creed, Anal. Chem. 80 (2008) 775-782. [132] T. J. Forehand, A. E. Dupuy, Jr. H. Tai, Anal. Chem. 48 (7) (1976) 999- 1001. [133] C. Maria Barra, M. Luisa Cervera, M. de la Guardia, R. Santelli, Anal. Chim. Acta. 407 (2000) 155–163. [134] H. Jiang, B. Hu, B.Chen, L. Xia, Anal. Chim. Acta. 634 (2009) 15–21. [135] T. Dagnaca, A. Padro, R. Rubioa, G. Raureta, Anal. Chim. Acta. 364 (1998) 19-30. [136] L. Davidowsk, P. Sarojam, Application note, PerkinElmer, Inc. Shelton, CT 06484 USA 93 [137] S. Ringmann, K. Boch, W. Marquardt, M. Schuster, G. Schlemmer, P. Kainrath, Anal. Chim. Acta. 452 (2002) 207–215. [138] M. Mar Gonzalez, M. Gallego, M. Valcarcel, Talanta 55 (2001) 135–142. [139] M. M. Sevaljevic, S. V. Mentus, N. J. Marjanovic, J. Serb. Chem. Soc. 66 (6) (2001) 419–427. [140] J-b. Shi, Z.Tang, Z.Jin, Q. Chi, B Hea, G.Jiang, Anal. Chim. Acta. 477 (2003) 139–147. [141] M. Bissen, F. H. Frimmel Fres. J. Anal. Chem. 367 (2000) 51–55. [142] M.Vergara Gallardo, Y. Bohari, A. Astruc, M. Potin-Gautier, M. Astruc, Anal. Chim. Acta. 441 (2001) 257-268. [143] S. Pedersen-Bjergaard, K.E. Rasmussen, Legemiddelanalyse, 503 s (2004). [144] R. Hahn, R. Schlegel, A. Jungbauer, J. Chromatogr. B, 790 (2003) 35–51. [145] Method 1669 Sampling Ambient Water for Trace Metals at EPA Water Quality Criteria Levels U.S. Environmental Protection Agency Office of Water, Engineering and Analysis Division (4303) 401 M Street S.W. Washington, D.C. ( 1996) [146] M. Segura, J. Munoz, Y. Madrid, C. Camara, Anal. Bioanal. Chem. 374 (2002) 513–51. [147] USEPA Determination of Trace Elements in Waters and Wastes by Inductively Coupled Plasma-Mass Spectrometry. 5.4 EPA Method 200.8, Washington (1994) [148] M. Yamanaka, Agilent Technologies application note (2000) 1–4. [149] USEPA Inorganic Arsenic in Water by Hydride Generation Quartz Furnace Atomic Absorption EPA Method 1632, Washington (1996) [150] Lanxess, Engineering information, Preliminary version, Arsenic separation from ground water using Lewatit FO 36 Ion Exchange/Iron Oxide Hybrid System, Leverkusen (2007). [151] W.S. Boom, US 4724082 (1988) (Dow Chemical Co.). [152] J. Biyan, S. Fei, G. Hu, S. Zheng, Q. Zhang, Z. Xu, J. Hazard. Mater. 161 (2009) 81-87. [153] M. Grafe, M.J. Eick, P.R. Grossl, A.M. Saunders, J. Environ. Qual. 31 (2002) 1115-1123 [154] S. Fendorf, M.J. Eick, P. Grossl, D.L. Sparks, Environ. Sci. Technol. 31 (1997) 315-320 [155] C.A. Impellitteri, Water Res. 38 (2004) 1207-1214 [156] Z. Gong, X. Lu, W. R. Cullen, X. Chris Le, J. Anal. At. Spectrom., 16 (2001) 1409-1413 [157] K. Nakamiya, Y. Shibata, H. Ito, J. S. Edmonds, M. Morita, Appl. Organo. Chem. 19 (2005) 282- 286. [158] J. A. Day, M. Montes-Bayon, A.P Voderhoide, J.A Caruso, Anal. Bioanal. Chem. 373 (2002) 664– 668. [159] J.S. Zhang, R.S. Stanforth, S.O. Pehkonen, J.Coll. Int. Sci. 306 (2007) 16–21 94 BIOGRAPHY Mr Nureddin A.A Ben Issa, date and place of birth 06. 01. 1966. Ttripoli libya. B.Sc. Chemistry (Tripoli University) 1990. Master degree, enrolled in graduate studies in 2001. at the TMF, Belgrade University, department of organic chemistry. Master's thesis entitled: synthesis and characteristic1,5-diazido-3-nitraza petana”, defended 15.09.2003, place of work, staff member in faculty of science (University of Al-Jabal Al-Garbi) Libya. Research activity: 1. Analysis of " water, inorganic compound, soil, concrete, metals and alloys using different methods as classical and instrumentation 2. Good Experience in instrumentation analysis ( Atomic absorption and UV- Visible - spectroscopy ) 3. Special study in pollution Caused by heavy metals in traffic, drinking water and sea water 4. Evaluation of natural silica in Abo-Gelan south of Tripoli and its uses 5. Nitrate analysis in drinking water (South of Tripoli) 6. Teaching courses program in “Analytical chemistry, Reference list: 1. N.B. Issa, V.N. Rajaković-Ognjanović, B.M. Jovanović, Lj.V. Rajaković, Determination of Inorganic Arsenic Species in Natural Waters-Benefits of Separation and Preconcentration on Ion Exchange and Hybrid Resins, Analitica Chimica Acta, 673(2010) 185-195 2. N.B. Issa, V.N. Rajaković-Ognjanović, A. D. Marinković, Lj.V. Rajaković, Separation and Determination of Arsenic species in water by selective exchange and hybrid resins, Analitica Chimica Acta, 706 (2011) 191-198. 3. N.B. Issa, A. D. Marinković, Lj.V. Rajaković, Separation and determination of dimethylarsenate in natural waters, J. Serb. Chem. Soc. 77 (6) (2012) 775–788 CONFERENCE 4. M. Zindah, A. A. Suliman, N. B. Issa, M. M. Zirg “Spectrophotometer Determination of Fe & V Complexes Using Pyrrole-2-Carboxylic Acid“ 2nd International Conference on Chemistry in Industry Saudi Arabian, International 95 Chemical Sciences Chapter of American Chemical Society and Bahrain Society of Chemists, p-1410, October 24-26, 1994, Manama, Bahrain. 5. Issa. Bagnie, N. Ben Issa, khaled. T, S. Elmangosh “Study the level of heavy metals in Tripoli coastal Seawater” Libyan Engineering Journal, p-58-68 , 1998 -38 6. N. Ben Issa, A. Abdalla, A. Swedan, Y. Abdalla, M. Derowesh , B. Saed “Studying the Concentration of Nitrate and Salts in Under Ground Water Wells in Located Area of Garian City“ The 10th International Chemistry Conference and Exhibition in Africa (10 ICCA), Book of abstracts p. 193, November 18-21, 2007, Benghazi, Libya. 7. N. Ben Issa, Branislava Jovanovic, Ljubinka Rajakovic, “A New Ion-Exchange And Sorption Procedure For Arsenic Removal From Water “ The International confferance Waste Waters, Municipal Solid Wastes And Hazardous wastes.p.34,April 06-09.2009 Zlatibor, Serbia 8. N.B. Issa, Lj. Rajaković, Efficiency of ion exchange resins for arsenic removal from water, European Conference on Analytical Chemistry, Euroanalysis, Innsbruck, 2009, P079-B2 Прилог 1. Изјава о ауторству Потписани/_""""'Јt_,,._~_о t_~_:ЈЈ_i.1)_1_/t/_А-_. _8_e_N _ IS._S_ A-____ _ бр~индекса~~~~~~~~~~~~~~~~~~~- Изјављујем да је докторска дисертација под насловом RAZVOJ 1 PRIMENA HIBRIDNIН SORВENATA ZA ODREDIVANJE 1 SELEKTIVNO UКLANJANJE ARSENA(III) i ARSENA(V) IZ VODE • резултат сопственог истраживачког рада, • да предложена дисертација у целини ни у деловима није била предложена за добијање било које дипломе према студијским програмима других високошколских установа, • да су резултати коректно наведени и • да нисам кршио/ла ауторска права и користио интелектуалну својину других лица. Потпис докторанда У Београду, О 3 . tf J.. J.iJ/J.. Прилог 2. Изјава о истоветности штампане и електронске верзије докторског рада Име и презиме аутора ___ NUREDDIN А.А. BEN ISSA Бр~индекса ________________________ _ Студијски програм __ -тl ___ iJ_4_L_i_Tt_t_tc__тt __ -t-'-1 f=-~'-'/G_'l"""'J_A- ______ _ Наслов рада __ ТНЕ DEVELOPMENT AND APPLICATION OF HYBRID SORBENTS FOR DETERMINA TION AND SELECTIVE REMOV AL OF ARSENIC(III) AND ARSENIC(V) FROM \VATER·-------------------~ Ментор ____ Ljublnka Rajakovic, professor ofTMF, Thesis Supervisor ______________________ _ Потписани/а __ CD.._f<_u_t,,__J 'и_z ю_· ·· ·· ·_;_;c __ -y-+-+--1Jr;_....___Чk_CL _ _ Изјављујем да је штампана верзија мог докторског рада истоветна електронској верзији коју сам предао/ла за објављивање на порталу Дигиталног репозиторијума Универзитета у Београду. Дозвољавам да се објаве моји лични подаци везани за добијање академског звања доктора наука , као што су име и презиме , година и место рођења и датум одбране рада. Ови лични подаци могу се објавити на мрежним страницама дигиталне библиотеке, у електронском каталогу и у публикацијама Универзитета у Београду . / Потпис докт,()ранда , .// У Београду , 3 -/ Ј · ,Ј.. О /,Д • Прилог 3. Изјава о коришћењу Овлашћујем Универзитетску библиотеку "Светозар Марковић" да у Дигитални репозиторијум Универзитета у Београду унесе моју докторску дисертацију под насловом: RAZVOJ 1 PRIMENA HIBRIDNIH SORВENATA ZA ODREDIV ANJE 1 SELEKTIVNO UКLANJANJE ARSENA(IП) i ARSENA(V) IZ VODE која је моје ауторско дело . Дисертацију са свим прилозима предао/ла сам у електронском формату погодном за трајно архивирање . Моју докторску дисертацију похрањену у Дигитални репозиторијум Универзитета у Београду могу да користе сви који поштују одредбе садржане у одабраном типу лиценце Креативне заједнице (Creative Commoпs) за коју сам се одлучио/ла . 1. Ауторство 2. Ауторство - некомерцијално @уторство - некомерцијално - без прераде 4. Ауторство- некомерцијално -делити под истим условима 5. Ауторство - без прераде 6. Ауторство - делити под истим условима (Молимо да заокружите само једну од шест понуђених лиценци , кратак опис лиценци дат је на полеђини листа) . Потпис докторанда УБеограду, Од.~- ~Ц..