Urinary trans,trans-muconic acid determined by liquid chromatography: application in biological monitoring of benzene exposure.
We describe a sensitive and specific high-performance liquid-chromatographic method for determining the benzene metabolite, trans,trans-muconic acid (ttMA) in urine by measuring ultraviolet absorbance at 265 nm. We mix 1 mL of urine sample with 2 mL of Tris buffer containing vanillic acid as internal standard (IS) and percolate this through a preconditioned ion-exchange column. After rinsing the column with phosphoric acid solution, acetate buffer, and deionized water, we elute the analytes with 2 mL of an equivolume solution of 1.5 mol/L sodium chloride and methanol. Of this, 5 microL is injected into the HPLC column. The mobile phase used consists of, per liter, 10 mL of acetic acid, 100 mL of methanol, and the rest 5 mmol/L sodium acetate. The flow rate was started at 1 mL/min and increased to 1.5 mL/min after 6 min. ttMA and IS were detected at 5.2 and 10.2 min, respectively. The lowest detection limit is 125 pg. Analytical recovery and reproducibility generally exceeded 90%. We validated the method with urine samples collected from normal persons and from refinery workers exposed to benzene concentrations < 1 microL/L. The results show that urinary ttMA is a promising biological marker for risk assessment of low-concentration benzene exposure.
WHO Collaborating Centre on Occupational Health, Department of Community Medicine, National University of Singapore, Kent Ridge.
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Lee
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Kok
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Ong
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D001554:Benzene / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D004784:Environmental Monitoring / Q000379:methods*; D006801:Humans; D012015:Reference Standards; D013011:Sorbic Acid / Q000031:analogs & derivatives* / Q000032:analysis; D014556:Urine / Q000737:chemistry; D014641:Vanillic Acid / Q000032:analysis
C005939:muconic acid; D014641:Vanillic Acid; D001554:Benzene; D013011:Sorbic Acid