A sensitive liquid chromatographic method for the spectrophotometric determination of urinary trans,trans-muconic acid.
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.
Lee
Bee Lan
BL
Department of Community, Occupational and Family Medicine, Faculty of Medicine, National University of Singapore, 16 Medical Drive, Singapore 117597, Singapore.
Ong
Her Yam
HY
Ong
Yeong Bing
YB
Ong
Choon Nam
CN
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
D015415:Biomarkers; C005939:muconic acid; D001554:Benzene; D013011:Sorbic Acid