Monoclonal antibody-mediated clean-up procedure for the high-performance liquid chromatographic analysis of chloramphenicol in milk and eggs

A simple, rapid and specific sample preparation method based on antibody-mediated clean-up for the determination of chloramphenicol (CAP) in milk and eggs was developed. Skimmed milk and centrifuged egg homogenates were filtered and directly applied to immunoaffinity columns which were prepared by coupling monoclonal antibodies against CAP to a carbonyldiimidazole-activated support. Using a 0.2 M glycine, 0.5 M NaCl (pH 2.8) solution as an eluent, the immunoaffinity columns can be used more than 30 times without a decrease in column capacity. In subsequent high-performance liquid chromatographic analysis, no matrix interferences were observed. Good recoveries were obtained at spiking levels of 1-100 micrograms kg-1. Due to the high specificity of the clean-up procedure, the limit of detection can be lowered by increasing the test portion. Concerning milk, the limit of detection was successfully lowered to 20 ng kg-1 by increasing the test portion to 11 (recovery 99%). The method was applied to eggs produced by hens treated with CAP. The results are compared with those obtained by solid-phase extraction using silica gel.