title: Simultaneous determination of six mercapturic acid metabolites of volatile organic compounds in human urine.
abstract: The widespread exposure to potentially harmful volatile organic compounds (VOCs) merits the development of practical and accurate exposure assessment methods. Measuring the urinary concentrations of VOC mercapturic acid (MA) metabolites provides noninvasive and selective information about recent exposure to certain VOCs. We developed a liquid chromatography-tandem mass spectrometry method for quantifying urinary levels of six MAs: N-acetyl-S-(2-carboxyethyl)-L-cysteine (CEMA), N-acetyl-S-(3-hydroxypropyl)-L-cysteine (HPMA), N-acetyl-S-(2-hydroxy-3-butenyl)-L-cysteine (MHBMA), N-acetyl-S-(3,4-dihydroxybutyl)-L-cysteine (DHBMA), N-acetyl-S-(2-hydroxyethyl)-L-cysteine (HEMA), and N-acetyl-S-(phenyl)-L-cysteine (PMA). The method provides good accuracy (102% mean accuracy) and high precision (3.5% mean precision). The sensitivity (limits of detection of 0.01-0.20 microg/L) and wide dynamic detection range (0.025-500 microg/L) make this method suitable for assessing VOC exposure of minimally exposed populations and those with significant exposures, such as cigarette smokers. We used this method to quantify MA levels in urine collected from smokers and nonsmokers. Median levels of creatinine-corrected CEMA, HPMA, MHBMA, DHBMA, HEMA, and PMA among nonsmokers (n = 59) were 38.1, 24.3, 21.3, 104.7, 0.9, and 0.5 microg/g creatinine, respectively. Among smokers (n = 61), median levels of CEMA, HPMA, MHBMA, DHBMA, HEMA, and PMA were 214.4, 839.7, 10.2, 509.7, 2.2, and 0.9 microg/g creatinine, respectively. All VOC MAs measured were higher among smokers than among nonsmokers, with the exception of MHBMA.
authors.affiliation: Emergency Response and Air Toxicants Branch, Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, NE, Mailstop F-47, Atlanta, Georgia 30341-3724, USA.
authors.forename: Yan S
authors.initials: YS
authors.lastname: Ding
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Blount
authors.forename: Liza
authors.initials: L
authors.lastname: Valentin-Blasini
authors.forename: Heather S
authors.initials: HS
authors.lastname: Applewhite
authors.forename: Yang
authors.initials: Y
authors.lastname: Xia
authors.forename: Clifford H
authors.initials: CH
authors.lastname: Watson
authors.forename: David L
authors.initials: DL
authors.lastname: Ashley
mesh_terms: D000111:Acetylcysteine / Q000378:metabolism / Q000652:urine*; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D012907:Smoking; D053719:Tandem Mass Spectrometry / Q000379:methods*; D055549:Volatile Organic Compounds / Q000378:metabolism / Q000652:urine*
chemical_list: D055549:Volatile Organic Compounds; D000111:Acetylcysteine