Primena prirodnih minerala kao senzora za elektrohemijska određivanja različitih jedinjenja u vodenoj i nevodenoj sredini

Abstract

Apstrakt: Pirit, halkopirit, galenit, arsenopirit i magnetit su sulfidni/oksidni monokristali veoma rasprostranjeni u prirodnom okruženju. Indikatorske elektrode na bazi ovih prirodnih materijala imaju izraženu mehaničkou otpornost, hemijsku inertnost, poluprovodljivost i netoksičnost. Zahvaljujući ovim karakteristikama primenjuju se kao elektrohemijski senzori za različita analitička određivanja u vodi i nevodenim rastvaračima. Minerali arsenopirit i magnetit su, pod uticajem sredine, skloni formiranju hidroksid/sulfidnog, odnosno hidroksid/oksidnog sloja koji služi kao senzor sa karakteristikama pH elektroda. Minerali, pirit, halkopirit i galenit, zahvaljujući jonima bakra inkorporiranim u kristalnu rešetku minerala, predstavljaju odlične redoks indikatorske elektrode osetljive na jone bakra. Indikatorske elektrode sa senzorima na bazi ovih minerala pokazuju stabilan potencijal, relativno brz odziv, linearnu zavisnost potencijala od koncentracije p-toluensulfonske kiseline sa sub-Nernstovskim nagibom (odnosi se na arsenopirit i magnetit), odnosno linearnu zavisnost potencijala od koncentracije Cu2+ jona sa sub-Nernstovskim nagibom (odnosi se na pirit, halkopirit i galenit), uz visoku selektivnost, dobru reproduktivnost dobijenih rezultata, potvrđenu inertnost u γ-butirolaktonu, propilenkarbonatu i smeši rastvarača voda-acetonitril, kao i uz mogućnost primene bez vremenskog ograničenja. Arsenopiritna i magnetitna elektroda su uspešno primenjene za acido-bazna određivanja benzoeve, salicilne i antranilne kiseline. Piritna, halkopiritna i galenitna elektroda su korišćene za redoks određivanja organskih jedinjenja ferocena, tiouree, tetrabutilamonijum-jodida i fenilhidrazina, kao i za redoks određivanje L-askorbinske kiseline u farmaceutskim preparatima u nevodenoj sredini. Relativna standardna devijacija određivanja ispitivanih jedinjenja manja je od ±1,00%.

Abstract: Pyrite, chalcopyrite, galena, arsenopyrite and magnetite are sulfide/oxide monocrystals widespread in the natural environment. Thanks to their mechanical resistance, chemical inertness, semiconductivity and non-toxicity, indicator electrodes based on these natural materials, have significant applications as electrochemical sensors for various analytical determinations in water-based and nonaqueous solvents. Minerals, arsenopyrite and magnetite, influenced by the environment, can form a hydroxide/sulfide or hydroxide/oxide layer on the surface of the mineral, which acts as a sensor with the characteristics of the pH electrodes. Minerals, pyrite, chalcopyrite and galena, thanks to copper ions incorporated into the crystal lattice of the minerals, are excellent redox indicator electrodes sensitive to copper ions. Indicator electrodes with sensors based on these minerals show a stable potential, relatively short response time, linear dependence of potential on the concentration of p-toluenesulfonic acid with sub-Nernstian slope (pertaining to arsenopyrite and magnetite), or linear dependence of potential on the concentration of Cu2+ ions with sub-Nernstian slope (pertaining to pyrite, chalcopyrite and galena), with high selectivity, good reproducibility of the obtained results, confirmed inertness in γ-butyrolactone, propylene carbonate and in water-acetonitrile solvent, as well as with the possibility of application without a time limit. Arsenopyrite and magnetite electrodes have been successfully used for acid-base determinations of benzoic, salicylic and anthranilic acid. Pyrite, chalcopyrite and galena electrodes have been used for redox determination of the organic compounds of ferrocene, thiourea, tetrabutylammonium iodide and phenylhydrazine as well as for the redox determination of L-ascorbic acid in pharmaceutical preparations in a non-aqueous media. The relative standard deviation of determination of the investigated compounds is less than ±1.00%.