An-Najah Staff

Two spectrophotometric methods are described for spectrophotometric determination of tiopronin in pharmaceuticals. They are based on the oxidation-reduction reaction between tiopronin and iron(III)-ferrozine complex [system I] or iron(III)-di-2-pyridyl ketone-2-thiophenoyl-hydrazone complex [system II]. The produced colored iron(II)-Ferrozine or iron(II)-di-2-pyridyl ketone-2-thiophenoyl-hydrazone complex absorbs at 562 nm and 656 nm, respectively. The effect of different factors such as; pH, reagent concentration, times, temperature and the tolerance amount of the common excipients have been reported. Applying the optimum working conditions, tiopronin can be determined over the range 0.2-8.6 and 0.5-17.0 ppm when using system I and II, respectively. The two methods offer high selectivity, sensitivity and accuracy with RSD less than 1.5% for five measurements. The proposed methods were applied successfully for the determination of tiopronin in Captimer tablets.