Fluorometric determination of phenol and p-cresol in urine by precolumn high-performance liquid chromatography using 4-(N-phthalimidinyl)benzenesulfonyl chloride.

A sensitive HPLC method for simultaneous determination of phenol and p-cresol in urine was developed. After acid hydrolysis of urine was conducted, phenol and p-cresol were extracted with diisopropyl ether and derivatized with 4-(N-phthalimidinyl)benzenesulfonyl chloride to give fluorescent sulfonyl esters. The labeling reactions were completed at 75 degrees C for 10 min. The fluorescent derivatives were separated on a reversed-phase column by a gradient elution with acetonitrile-water and detected by fluorescence measurement of excitation at 300 nm and emission at 410 nm. The detection limits (signal-to-noise ratio = 3) for phenol and p-cresol were 0.17 and 0.25 pmol per injection, respectively. The within-day and day-to-day relative standard deviations were 2.31-3.76 and 4.36%, respectively, for phenol and 1.99-4.56 and 3.71%, respectively, for p-cresol. The concentrations (means) of phenol and p-cresol in normal human urine were 67.3 and 167.9 nmol/mg creatinine, respectively.