QUANTIFICATION OF BENZOCAINE AND ITS METABOLITES IN CHANNEL CATFISH TISSUES AND FLUIDS BY HPLC

Methods for extraction and gradient HPLC quantification were developed for benzocaine (BZ) and three of its metabolites to be used in conjun ction with a reverse isotope technique. The metabolites were p-aminobe nzoic acid (PABA), acetyl-p-aminobenzoic acid (AcPABA) and acetylbenzo caine (AcBZ). The matrixes studied were white muscle, red muscle, skin , liver, trunk kidney, head kidney, plasma and the bile of channel cat fish. Analytes were validated for each of the compounds at 25 and 100 nmol per sample in the Various tissues and fluids. The intraday variab ility (R.S.D.) was less than 13% in all tissues and fluids except for BZ in the liver. Recoveries varied from matrix to matrix for each anal yte. The highest recoveries were obtained from plasma which ranged fro m 82.8-99.8% depending on the concentration. The average recovery of t he compounds from tissues was between 50 and 78%, except for liver whe re the recovery of PABA and BZ was below 30%. Detection was by UV abso rbance at 286 nm and the linear range was 2.5-15 nmol 100 ml(-1) for a ll analytes. The method was selective, no interference peaks coeluted with the analytes. (C) 1997 Elsevier Science B.V.