Hollow-fiber liquid-phase microextraction based on carrier-mediated transport for determination of urinary methyl hippuric acids

Hollow-fiber liquid-phase microextraction based on carrier-mediated transport for analysis of methyl hippuric acids in aqueous samples is described. Under optimized conditions, relative recoveries of 83%-98% and limits of detection of 2-3 mu g L-1 were obtained, with linear calibration curves for the three isomers in the range of 10-50,000 mu g L-1. The method was applied for the determination of urine samples of volunteers at various working environments.