Li Quanmin, Gao Linxiao
College of Chemistry and Environmental Science, Henan Normal University, The Key Laboratory of Environmental Pollution Control Technology of Henan Province, USA.
Anal Sci. 2009 Jan;25(1):89-93. doi: 10.2116/analsci.25.89.
A novel and simple spectrophotometric method for the determination of tiopronin with sodium 1,2-naphthoquinone-4-sulfonate (NQS) is established in this paper. The detailed mechanism is proposed and discussed. It is based on the fact that tiopronin can catalyze the reaction between sodium 1,2-naphthoquinone-4-sulfonate and hydroxyl ion to form 2-hydroxy-1,4-naphthoquinone in a buffer solution of pH 13.00 at the maximal absorption wavelength of 445 nm. When tetradecyl benzyl dimethyl ammonium chloride (Zeph) is added to the solution, the sensitivity of the reaction is improved. Beer's law is obeyed in a range of 0.39 - 15.67 microg mL(-1). The equation of linear regression is A = 0.11749 + 0.05914C (microg mL(-1)), with a linear correlation coefficient of 0.9973. The detection limit is 0.2 microg mL(-1), RSD is 0.88% and the recovery rate is in the range of 96.6 - 103.9%. Furthermore, the method has been validated and successfully applied to the determination of tiopronin in pharmaceutical samples.
