HPLC WITH FLUORESCENCE DETECTION OF URINARY PHENOL, CRESOLS AND XYLENOLS USING 4-(4,5-DIPHENYL-1H-IMIDAZOL-2-YL)BENZOYL CHLORIDE AS A FLUORESCENCE LABELING REAGENT

A simple and sensitive HPLC method for the determination of phenolic c ompounds, i.e., phenol (Phe), cresols (Cres) and xylenols (Xyls), was developed. After a pre-column fluorescence derivatization of these com pounds with 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) at 60 degrees C for 30 min, 11 DIB derivatives were successfully sepa rated within 50 min with an ODS column using CH3CN-H2O-CH3OH (25 + 22 + 53, v/v) as the eluent. The detection limits of DIB derivatives at a signal-to-noise ratio of 3 ranged from 0.15 to 1.09 mu M (0.2-1.6 pmo l per 20 mu l) The precision of the proposed method for both within- a nd between-day assays of free and total phenol related compounds was s atisfactory (RSD < 9.5%). By the proposed method, Phe and p-Cre could be detected in normal urine samples, and the calculated concentrations of foe Phe and p-Cre in unhydrolysed urine samples were 1.5 +/- 1.3 a nd 23.9 +/- 24.3 mu M and those of total Phe and p-Cre in hydrolysed u rine samples were 87.3 +/- 81.2 and 200.7 +/- 195.4 mu M (n = 21), res pectively.