A Sensitive HPLC Method for Determination of Mandelic Acid in Urine, and Its Application to Biological Monitoring of Ethylbenzene-exposed Chinese Workers

Abstract

AbstractA highly sensitive high-pressure liquid chromatography (HPLC) method was developed for determination of mandelic acid (MA) in urine as a marker of exposure to ethylbenzene at low concentrations. This was achieved by the use of a mobile phase (acetonitrile: 60% perchloric acid: water = 50 ml: 100 μl: 950 ml) that has no absorption at 200 nm, the wavelength at which MA shows intense absorption. The detection limit was 0.07 mg/L urine, and the recovery rate was 101% (CV: 2.7%) when MA was added at 250 mg/L to ten urine samples from non exposed subjects. The method was applied for MA determination, in parallel to a method previously developed, to 641 urine samples (from 360 ethylbenzene-exposed workers and 281 nonexposed subjects), and the results were analyzed by regression analysis to examine the relationship between ethylbenzene exposure concentrations and urinary MA concentrations. A smaller intercept on the axis (essentially zero) and a larger correlaiion coefficient (about 0.7) indicate that the...