Determination of urinary S-phenylmercapturic acid by liquid chromatography-tandem mass spectrometry.
Urinary S-phenylmercapturic acid (S-PMA) is considered a useful biomarker for the measurement of low levels of benzene exposure, related to occupational exposure, smoking habits or environmental pollution. S-PMA quantitative analysis requires highly sensitive and specific techniques and purification procedures, mainly based on liquid-liquid or solid-phase extraction, which result in time expensive analyses. A method was developed for the quantitative determination of S-PMA in urine by using a simple, reproducible and easily automatizable HPLC purification followed by LC/ESI-NI/MS2 analysis. In order to reduce the cost of the analysis, related to the use of expensive labeled standards, p-bromo-S-phenylmercapturic acid (p-Br-S-PMA) was synthesized, characterized and used as internal standard. The feasibility and efficacy of the proposed method were examined by constructing calibration curves in the range from 6.2 to 200 microg/l and data were analyzed in terms of linearity and statistical parameters. The detection limit, related to the purification of 1 ml urine sample is 5 microg/l. The method was applied to the analysis of 12 urine samples from smoker subjects non-occupationally exposed to benzene. S-PMA urinary levels ranged from 13.6 to >200 microg/l, suggesting a high influence of life style in the S-PMA excretion. The proposed analytical method is suitable for the biological monitoring of both smoker and non-smoker workers, occupationally exposed to benzene. By processing at least 2 ml of urine samples, the method appears to be also useful for the evaluation of benzene uptake due to the environmental pollution.
Pieri
M
M
Dipartimento di Medicina Interna e Medicina Pubblica, Università di Bari, Piazza Giulio Cesare 1, I-70126 Bari, Italy. maria.pieri@unina2.it
Miraglia
N
N
Acampora
A
A
Genovese
G
G
Soleo
L
L
Sannolo
N
N
D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000652:urine*; D001554:Benzene / Q000633:toxicity; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005240:Feasibility Studies; D006801:Humans; D016273:Occupational Exposure; D012680:Sensitivity and Specificity; D012907:Smoking / Q000652:urine; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
C053003:S-phenyl-N-acetylcysteine; D001554:Benzene; D000111:Acetylcysteine