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Flow Injection Analysis with Two Parallel Detectors: Potentiometric and Spectrophotometric Determination of Thiols and Ascorbic Acid in Mixture

Anita Martinović , Štefica Cerjan-Stefenović , Njegomir Radić

J. Chem. Metrl. (2008), 2:1 ; 1-12

1 Department of Chemistry, Faculty of Science and Education, University of Mostar, Matice hrvatske bb, Mostar, Bosnia & Herzegovina

2 Laboratory for Analytical Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 20, Zagreb, Croatia

3 Department of Chemistry, Faculty of Chemistry and Technology, University of Split, Teslina 10/V, Split, Croatia

Abstract: One flow injection analysis (FIA) procedure for the successive potentiometric and spectrophotometric determination of ascorbic acid (AA) and thiols (cysteine, cys; N-acetyl-L-cysteine, NAC; penicillamine, pen; glutathione, glu) in mixtures has been described. The potentiometric FIA signal is based on the reaction of formation the sparingly soluble salts, RSAg, between thiols (designated also as RSH) and Ag + ions. Ascorbic acid has had no influence on potentiometric signal at any experimental concentration. The spectrophotometric FIA signal is based on redox-reaction of chosen compounds with 1,10-phenanthroline-iron(III) complex. For potentiometric determination of thiols and spectrophotometric determination of selected compounds a rectilinear calibration graphs were obtained. .

Key words: Flow-injection analysis, Thiols, Ascorbic acid, Potentiometry, Spectrophotometry