[Determination of S-phenylmercapturic acid in human urine by HPLC-MS].

Objective: To establish the method to determine S-phenylmercapturic acid (S-PMA) in human urine, and the method was actually applied to determine S-PMA concentrations in the human urine from subjects occupationally exposed to benzene.
Methods: After the urine samples are hydrolyzed by acidification, and modulated to suitable pH value. S-PMA is obtained by liquid-liquid extraction and separated by HPLC. Use negative ion mode electric spray ion source MS to measure, and select the molecular ion peak m/z 238 and quantitative analysis is performed by peak area.
Results: This method has good linear in the range of 5-320 microg/L, and r = 0.9994 +/- 0.0003, and the detection limit is 1.2 microg/L (S/N = 3), recovery percentage is 86.8%-94.2%. Both the intra- and inter-day precisions are less than 7%. Use this method to measure the S-PMA in the end-of-shift urine of 55 workers occupationally exposed to benzene and perform the regression analysis for the S-PMA concentration and the benzene concentration in air (r = 0.8035, P < 0.05).
Conclusion: The method established by this research is rapid, sensitive and selective, and the results are accurate and reliable.