Evaluation of sample preparation for control of chloramphenicol residues in porcine tissues by enzyme-linked immunosorbent assay and liquid chromatography

The effects of sample preparation on the determination of chloramphenicol (CAP) residues by enzyme-linked immunosorbent assay (ELISA) and liquid chromatography (LC) were investigated. First, the biological matrices were treated with extraction solutions, which were mixtures of acetate buffer and acetonitrile. The isolation of CAP from previously spiked samples was performed by homogenization or ultrasonication. For clean-up, the suitability of solid phase extraction columns (in reverse phase (RP) or mixed mode) was compared. The level of CAP in tested samples was determined by a commercial ELISA test (R-Biopharm) and LC with UV detection at 270 nm, after separation on a RP column. It was found that the best isolation from interfering, endogenous compounds was obtained after homogenization of sample with a mixture of acetate buffer (pH 5.0) and acetonitrile (2:8, v/v). The clean-up of the sample extracts in a mixed mode rather than reverse phase was more efficient. The recovery of CAP from spiked pig muscle was 82%, and from kidney, 85%. The same analytical protocol is suitable for CAP screening in animal tissues by ELISA as well as by LC. (C) 2002 Elsevier Science B.V. All rights reserved.