A novel method for the determination of tiopronin by using potassium ferricyanide as spectroscopic probe reagent in pharmaceutical and urine samples

摘要

In this paper, a novel method has been established to determine tiopronin using potassium ferri- cyanide as spectroscopic probe reagent. It has been demonstrated that Fe(III) is reduced to Fe(II) by tiopro- nin, and the in situ formed Fe(II) reacts with potassium ferricyanide to form soluble Prussian blue. Beer's law is obeyed in the range of tiopronin concentration of 0.040-9.00 μg/mL at the maximal absorption wavelength of 735 nm. The linear regression equation is A = 0.0153 + 0.1605c (μg/mL) with a correlation coefficient of 0.9997 and the apparent molar absorption coefficient of 2.6 × 104 L/mol cm. The detection limit is 0.030 μg/mL and RSD is 1.3%. The parameters with regard to determination have been optimized and the reaction mechanism has been discussed. This method has been successfully applied to determine tiopronin in phar- maceutical and urine samples with satisfactory results.