DETECTION OF BENZTHIAZIDE BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY THERMOSPRAY MASS-SPECTROMETRY

Benzthiazide, a banned drug in the Olympic Games, is difficult to confirm by GC-MS after methylation of urine extracts. Organic acids are added to the LC effluent to detect this drug by LC-thermospray (TSP) MS. An organic acid with a small pK(a) value is useful for detecting benzthiazide in the positive-ion mode. In the negative-ion mode, the highest sensitivity for benzthiazide was obtained by using HOCH2COOH. When LC-TSP-MS is used to detect benzthiazide, FCH2COOH and ClCH2COOH are useful organic acids in the positive-ion mode and HOCH2COOH, CH3CH2COOH and FCH2COOH in the negative-ion mode. FCH2COOH is useful in both the positive- and negative-ion modes. ClCH2COOH is a useful organic acid for detecting the molecular ion of benzthiazide.