Determination of penicillamine or tiopronin in pharmaceutical preparations by flow injection analysis

Two flow injection analysis (FIA) methods, using spectrophotometric detection, are proposed for the determination of penicillamine or tiopronin [N-(2-mercaptopropionylglycine)]. The procedures are based on the formation of yellow complexes between these thiol-containing drugs and Pd(II), in a 1 M or 0.25 M HCl medium, respectively. With peak height as a quantitative parameter, penicillamine is determined over the range 1.0 x 10(-5)-7.0 x 10(-4) M; for tiopronin the range is 1.0 x 10(-5)-6.0 x 10(-4) M. The methods have been applied to the routine determination of the drugs in pharmaceutical preparations.