title: An electrospray ionization tandem mass spectrometry based system with an online dual-loop cleanup device for simultaneous quantitation of urinary benzene exposure biomarkers trans,trans-muconic acid and S-phenylmercapturic acid.
abstract: An electrospray ionization tandem mass spectrometry (ESI-MS/MS) system with an online dual-loop cleanup device was developed for simultaneous quantitation of the urinary benzene exposure biomarkers trans,trans-muconic acid (ttMA) and S-phenylmercapturic acid (SPMA). The cleanup device was constructed from an autosampler, two electrically operated two-position switching valves, a reversed-phase C18 trap cartridge, a 200-microL loop, and two solvent-delivery pumps. The device was interfaced directly with a triple-quadrupole mass spectrometer and fully controlled by computer software and hardware. Because isotope dilution by introducing 13C-labeled ttMA and SPMA as internal standards was employed, the precision of the analytical system was high (for ttMA, intra- and inter-day CV values ranged from 3.82-4.53%; for SPMA, 2.13-7.06%). The calibration curves obtained using human urine spiked with ttMA were linear from 15.6-4000 microg/L (R = 0.9998) and SPMA at concentrations from 0.78-200 microg/L (R = 0.9993). The method detection limit (MDL) for SPMA was 0.23 microg/L. The MDL of ttMA could not be determined accurately because of unavailability of an appropriate blank urine matrix, but was estimated to be lower than 7.43 microg/L. Without tedious manual sample cleanup procedures the analytical system is fully automated and is therefore useful for high-throughput simultaneous determination of urinary ttMA and SPMA. The sample throughput is roughly 100 samples per day. With the selectivity and the sensitivity provided by MS/MS detection, the analytical system can be used for large-scale monitoring of environmental or occupational exposure of humans to benzene.
authors.affiliation: Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan 704, Taiwan.
authors.forename: Lung-Cheng
authors.initials: LC
authors.lastname: Lin
authors.forename: Jeng-Fu
authors.initials: JF
authors.lastname: Shih
authors.forename: Tung-Sheng
authors.initials: TS
authors.lastname: Shih
authors.forename: Yu-Jang
authors.initials: YJ
authors.lastname: Li
authors.forename: Pao-Chi
authors.initials: PC
authors.lastname: Liao
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000652:urine*; D001554:Benzene; D001555:Benzene Derivatives / Q000378:metabolism*; D015415:Biomarkers / Q000032:analysis; D003201:Computers; D016273:Occupational Exposure; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D013011:Sorbic Acid / Q000031:analogs & derivatives* / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D001555:Benzene Derivatives; D015415:Biomarkers; C005939:muconic acid; C053003:S-phenyl-N-acetylcysteine; D001554:Benzene; D000111:Acetylcysteine; D013011:Sorbic Acid