The development of a rapid immunobiosensor screening method for the detection of residues of sulphadiazine

A rapid imununoassay using an optical biosensor (BIAcore(TM)) for determini ng the presence of sulphadiazine (SDZ) residues in pig bile was developed. SDZ,cas immobilised onto the surface of a dextran-coated silicon chip and a solution containing SDZ antibody, sample and buffer was injected over the chip surface. The level of antibody binding to the chip was determined afte r 20 s and the surface of the chip was then regenerated over a 1-min period prior to another sample injection taking place. Standard curves were const ructed to allow quantification of SDZ presence in sample. Concentrations ra nging from 0 to 10.64 mu g ml(-1) SDZ were detected in bile samples taken f rom experimentally fed pigs and randomly selected pigs taken from a local s laughterhouse. These results were compared to the concentrations of SDZ det ected by high-performance liquid chromatography: in associated tissues. Whe n concentrations in bile exceeded 0.6 mu g ml(-1) SDZ, the corresponding ed ible tissue was above the maximum residue level (MRL), i.e. 0.1 mu g g(-1) in 13 out of 14 cases. Wizen the bile concentration was less than 0.6 mu ml (-1) the associated tissue concentrations never exceeded rite MRL. This exp eriment has indicated that biosensor analysis of bile is a highly effective method for detecting violative SDZ residues in meat.