Measurement of Benzylmercapturic Acid in Human Urine by Liquid Chromatography-Electrospray Ionization-Tandem Quadrupole Mass Spectrometry

Abstract

A method based on liquid chromatography (reversed-phase)-electrospray (negative) ionization-tandem triple quadrupole mass spectrometry [LC-ESI(-)-MS-MS], in the multiple reaction monitoring mode, was developed for determination of urinary benzylmercapturic acid (BMA). Isotope dilution through introduction of (13)C(6)-labeled BMA was employed as an internal standard, achieving intra- and interrun precision ranges of 2.32-2.95% and 2.24-4.97%, respectively. The calibration curve obtained with BMA-spiked blank human urine was linear from 0.5-120.0 microg/L; the correlation coefficient of the calibration curve was 0.999. The method limit of quantification was 0.5 microg/L; mean BMA recovery was 97.56%. The analytical method was used to analyze urine samples collected from workers involved in the manufacture of adhesive tape who had been exposed to toluene. The method appears to provide sensitive, specific, and reliable testing for urinary BMA to determine occupational exposure to toluene.

Validation of an HPLC–MS/MS method for the simultaneous determination of phenylmercapturic acid, benzylmercapturic acid and o-methylbenzyl mercapturic acid in urine as biomarkers of exposure to benzene, toluene and xylenes

“…1a-c, respectively). Our results on the negative ionization of PMA and BMA are consistent with those previously reported [7,28]. Thus, for HPLC-MS/MS analysis in MRM mode, m/z 238 → 109, 252 → 123, and 266 → 137 were selected as the most sensitive transitions for PMA, BMA and MBMA, respectively.…”

Fast determination of urinary S-phenylmercapturic acid (S-PMA) and S-benzylmercapturic acid (S-BMA) by column-switching liquid chromatography–tandem mass spectrometry

“…Its use as a biomarker of toluene exposure has increased since then [25][26][27] and -similar to S-phenylmercapturic acid -its determination has been proposed to be more specific at low-level-exposures than the "classic" urinary biomarkers o-cresol or hippuric acid [28]. S-BMA is formed after o-sulfonation of benzyl alcohol by sulfotransferases and subsequent conjugation of the sulphate ester with glutathione, as reported for various xenobiotics like, e.g.…”

“…Methods published so far for the determination of urinary mercapturic acids of benzene and toluene involve mainly LC-MS-MS [26,27,32,33,34], LC-MS [35] or GC-MS after derivatisation of the mercapturic acids with carcinogenic diazomethane [15,31]. However, most of these methods determine only one metabolite [15,23,27,28,31,32,33,35].…”

“…However, most of these methods determine only one metabolite [15,23,27,28,31,32,33,35]. Moreover, many methods require extensive manual sample preparation like liquid-liquid-extraction with ethyl acetate [15,31] or solidphase extraction with anion-exchange cartridges [26,32].…”