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

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.