title: Validation of an HPLC-MS-MS method for the determination of urinary S-benzylmercapturic acid and S-phenylmercapturic acid.
abstract: A high-performance liquid chromatography-tandem mass spectrometric (HPLC-MS-MS) method is presented and evaluated for the determination of S-benzylmercapturic acid (S-BMA) and S-phenylmercapturic acid (S-PMA) in human urine. Both of these compounds are important for occupational health owing to their use as biomarkers of exposure to toluene and benzene, respectively. Toluene is used extensively as a solvent, and the health hazards of benzene have been well established. The optimized urine sample preparation scheme consists of solid-phase extraction (SPE) followed by an acetone wash. The chromatographic analysis consists of a reversed-phase gradient system, which uses electrospray ionization in negative-ion mode with a triple-quadrupole mass spectrometric detector. Accuracy and precision of this method are demonstrated by a series of recovery studies of spiked human urine and synthetic urine substitute. Spike levels at 1, 2, 6, 8, and 30 ng/mL for both analytes demonstrate average recoveries (accuracy) ranging from 99 to 110%. Precision as measured by the relative standard deviation (%RSD) of multiple samples (n=9) at each concentration level was 5.3% or less for both analytes in urine. The limit of detection (LOD) is approximately 0.2 ng/mL for S-BMA and S-PMA. This data, other figures of merit and other factors, such as ion suppression of the electrospray ionization source, are discussed.
authors.affiliation: U.S. Department of Health and Human Services, Centers for Disease Control, National Institute for Occupational Safety and Health, Division of Applied Research and Technology, Taft Laboratory C-23, 4676 Columbia Parkway, Cincinnati, OH 45226, USA. cbhymer@cdc.gov
authors.forename: C
authors.initials: C
authors.lastname: B'Hymer
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000652:urine; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: C053003:S-phenyl-N-acetylcysteine; D000111:Acetylcysteine; C029319:S-benzyl-N-acetyl-L-cysteine