Flow Injection Chemiluminescence Determination of Thiol-Containing Drugs Based on a Quinine-Sensitized Permanganate Reaction

Abstract

A new flow injection chemiluminescence method is presented for the determination of four thiol-containing drugs, cysteine, N-acetylcysteine, glutathione, and captopril. It was found that the oxidation of these drugs with potassium permanganate accompanied by weak chemiluminescence in acidic condition. The presence of quinine sulfate enhanced chemiluminescence signal greatly. The method allows to determine 0.02–2 µg mL−1 cysteine, 0.05–2 µg mL−1 N-acetylcysteine, 0.05–2 µg mL−1 glutathione, and 0.02–1 µg mL−1 captopril with limits of detection of 0.01 µg mL−1, 0.02 µg mL−1, 0.02 µg mL−1, and 0.006 µg mL−1, respectively. The relative standard deviations were less than 2% (n = 11) and the sample measurement frequency was about 120 samples h−1. The application of this method was demonstrated by the analysis of cysteine and captopril in some pharmaceutical preparations.