MATERIALS AND METHODS

Hippuric acid was determined in urine by using Ogata’s (1987) method with slight modifications. The chromatography system consisted of a HPLC pump (Jasco, Model PU-980 Intelligent HPLC pump), a UV/VIS detector (Jasco, Model UV-970/975, Intelligent UV/VIS detector) and a LiChrosorb RP18-5, 200 x 4.6 mm column (HICHROM). HPLC mobile phase consisted of a mixture of 5mM KH2PO4 (pH: 2.5)/CH3CN (90/10). A variable flow was used throughout the monitoring of the effluent. The intelligent HPLC pump provided us a programmable flow variation as could be seen in Figure 1. The effluent was monitored at 225 nm and the total assay was carried out at the ambient air temperature.