title: A sensitive liquid chromatographic method for the spectrophotometric determination of urinary trans,trans-muconic acid.
abstract: Benzene is a human carcinogen and its metabolite, urinary trans,trans-muconic acid (ttMA), is a biomarker for risk assessment. However, most of the existing methods were not sensitive enough for monitoring of low level exposure. This paper describes a HPLC-UV method for ttMA determination with enhanced selectivity and sensitivity. A 30 mg OasisMAX cartridge was used to clean-up 50 microl of urine sample and gradient elution was performed on a Zorbax SB-C(18) column (30 degrees C). ttMA was detected at wavelength 263 nm using a UV diode array detector (DAD). The two mobile phases used were (A) 150 mM ortho-phosphoric acid containing of 9% (v/v) methanol; and (B) 125 mM ortho-phosphoric acid containing 30% (v/v) acetonitrile. The method was validated with 61 urine samples collected from non-occupationally benzene exposed individuals and 14 quality control specimens from an international quality assessment scheme. The urinary ttMA concentrations (mean+/-S.D.microg/g creatinine) were 90+/-34 for smokers (n=26), 49+/-39 for non-smokers (n=21) and 23+/-18 for non-smoking hospital staff (n=14). A correlation coefficient, r=0.99 was found with 14 external quality specimens for ttMA ranged from 0.4 to 6.8 mg/l. The recovery and reproducibility were generally over 90% and the detection limit was 5 microg/l.
authors.affiliation: Department of Community, Occupational and Family Medicine, Faculty of Medicine, National University of Singapore, 16 Medical Drive, Singapore 117597, Singapore.
authors.forename: Bee Lan
authors.initials: BL
authors.lastname: Lee
authors.forename: Her Yam
authors.initials: HY
authors.lastname: Ong
authors.forename: Yeong Bing
authors.initials: YB
authors.lastname: Ong
authors.forename: Choon Nam
authors.initials: CN
authors.lastname: Ong
mesh_terms: D001554:Benzene / Q000633:toxicity; D015415:Biomarkers / Q000652:urine*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004781:Environmental Exposure / Q000032:analysis; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012907:Smoking / Q000652:urine; D013011:Sorbic Acid / Q000031:analogs & derivatives* / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D015415:Biomarkers; C005939:muconic acid; D001554:Benzene; D013011:Sorbic Acid