Electrospray Ionization Tandem Mass Spectrometry (ESI-MS/MS) Analysis of 1-Bromopropane Mercapturic Acid in Human Urine

Details

• Personal Author:
  Cheever KL ; DeBord, D. Gayle ; Marlow, Kate L. ; Stinson D ; Teass AW
• Description:
  1-Bromopropane (1-BP, CAS 106-95-5), used as an alternative solvent to chlorofluorocarbons and 1,1,1-trichloroethane, has been reported to cause reproductive and neurotoxicity in male rats. The related 2-bromopropane has been shown to cause similar toxicity in rats as well as amenorrhea, oligozoospermia, and anemia induction in workers. Although the mechanism of action of 1-BP has yet to be explained, it is thought that metabolic activation to reactive intermediates may be important. Metabolism of 1-BP is complex and is reported to occur by pathways which include debromination, oxidation by CYP2E1 and glutathione S-conjugation. 3-Bromopropionic acid and n-propanol are reported urinary metabolites of 1-BP whereas the glutathione conjugate, S-n-propyl-glutathione is further cleaved to S-n-propyl-L-cysteine and further to mercapturic acids N-acetyl-S-(n-propyl)-L-cysteine (M1), N-acetyl-S-(n-propyl)-L-cysteine-S-oxide (M2), N-acetyl-S-(2-carboxyethyl)-L-cysteine (M3), and N-acetyl-S-(3-hydroxy-n-propyl)-L-cysteine (M4). A potential biomonitoring method was developed to measure urinary levels of (M1), (M2), (M3) and (M4). The mercapturic acid standards as well as the stable isotope-labeled analog of (M1) internal standard were synthesized using the general procedure of van Bladern et al. (1980). A BenchMate II robotic workstation was used to automate sample preparation. Bond Elute 500 mg C18 SPE columns were conditioned with acetone, MeOH (5% HCl) and 5% MeOH in H2O pH 3. Samples were mixed with internal standard and loaded onto columns. A fraction containing >90% of 1-BP metabolites was collected in 3-mL acetone, reduced to dryness under N2 and dissolved in 1 mL MeOH for HPLC-MS/MS (ThermoQuest Finnegan LCQ tandem mass spectrometer) analysis on a 150 X 2 mm Phenomenex Aqua 3µm C18 300A column. Chromatographic standards were chromatographed using a 10-min linear gradient H2O 1% acetic acid to MeOH 1% acetic acid at 300 microliters/min to elute the compounds of interest within 10 min. During the chromatographic run the mass spectrometer was operated in multiple segments using ESI-MS/MS, in the positive ion mode for detection of protonated (M1), (M2), (M3) and (M4) and Selected Reaction Monitoring of major transition products. Urine samples fortified with a mixture of standards were mixed with 10 micrograms/mL of internal standard and processed for evaluation of recovery, limits of detection (LOD) and limits of quantitation (LOQ). Calibration of (M1), (M2), (M3) and (M4) was linear from 30 - 10000 ng/mL (r(2)>0.99). The sample preparation and analysis appears to offer significant advantages over typical preconcentration and derivatization procedures that would be required for GC-MS analysis of these compounds. Thus, 1-BP internal exposure levels for various exposure situations can be rapidly determined by analysis of these metabolites in a single assay using a selective automated sample preparation system. [Description provided by NIOSH]
• Subjects:
  Biomarkers Chemistry Chemistry, Analytic Chromatography Energy Metabolism Environmental Monitoring Mass Spectrometry Occupational Health Safety Urine
• Keywords:
  Analytical-chemistry Analytical-methods Analytical-processes Chemical-processing Chemical-properties Chromatographic-analysis Exposure-assessment Mass-spectrometry Metabolites Urinalysis Urine-chemistry

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• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  District of Columbia ; Ohio ; OSHA Region 3 ; OSHA Region 5 ; Virginia ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  DART - Division of Applied Research and Technology
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  115-116
• NIOSHTIC Number:
  nn:20027267
• Citation:
  International conference on occupational and environmental exposures of skin to chemicals: science and policy, September 8-11, 2002, Washington, DC. Morgantown, WV: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 2002 Sep; :115-116
• Federal Fiscal Year:
  2002
• Peer Reviewed:
  False
• Source Full Name:
  International conference on occupational and environmental exposures of skin to chemicals: science and policy, September 8-11, 2002, Washington, DC
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:d7caeff546bbfbd652a7b4efc8c1f431f89cacc4063f181b457cddd06c1adfaa0539183d28f4efa61041e7821dca8ddf99283fe7a7b2ac0b79a2613e03a05f10
• Download URL:
  https://stacks.cdc.gov/view/cdc/197519/cdc_197519_DS1.pdf
• File Type:
  [PDF - 444.49 KB ]