Spectrophotometric Determination of Tiopronin in Pharmaceutical Samples by Phosphorus Molybdenum Blue

Abstract

A novel method is established for spectrophotometric determination of tiopronin by phosphorus molybdenum blue. It is based on the fact that PO4 3reacts with Mo7O24 6in 0.47 mol/L H2SO4 solution to form a product of phosphorus-molybdenum heteropoly acid ([H2PMo12O40] -) which is reduced to phosphorus molybdenum blue (H3PO4•10MoO3•Mo2O5) by tiopronin. The absorbance of phosphorus molybdenum blue is measured at the absorption maximum of 730 nm and the amount of tiopronin can be determined based on this absorbance. Absorbance is linear with the concentration of tiopronin in the range of 1.6-40 µg/mL and the regression equation is A = -0.1193 + 0.01927c (µg/mL) with a correlation coefficient of 0.9989 and the apparent molar absorption coefficient of 3.14 × 10 3 L/(mol cm). The detection limit and the RSD are 1 µg/mL and 0.92 %, respectively. Thus, the method is validated and commonly available to determine tiopronin in pharmaceutical samples.

Determination of tiopronin content in drug by copper(I)-cuproine spectrophotometry

“…Therefore, the determination of tiopronin content is of great importance. Up to now, spectrophotometry [1][2], kinetic spectrophotometry [3][4], flow injection [5][6], chemiluminescence [7], electrochemiluminescence [8], LC-MS/MS [9] and LC-ESI-MS [10] have been used to determinate the content of TPN. In these literature, spectrophotometry is a commonly used method owing to its simplicity, rapidity and cheap instrument.…”