Flow-injection fluorimetric determination of penicillamine and tiopronin in pharmaceutical preparations

Abstract

Two flow-injection methods for the fluorimetric determination of penicillamine and tiopronin are proposed. The procedures are based on the oxidation of these drugs by thallium(III). In hydrochloric acid medium the fluorescence of thallium(I) formed in the oxidation of penicillamine or tiopronin is monitored using excitation and emission wavelengths of λ ex = 227 nm and λ em = 419 nm respectively. Linear calibration graphs were obtained between 3 × 10 −7 and 8 × 10 −6 M for penicillamine and between 8 × 10 −7 and 2 × 10 −5 M for tiopronin with sampling frequencies of 90 and 45 samples h −1 respectively. The relative standard deviations were in the ranges 0.48-0.29% for penicillamine and 1.04-0.31% for tiopronin. The applicability of the method to the determination of both drugs in pharmaceutical preparations was demonstrated by investigating the effect of potential interferences and by analysis of commercial preparations.