Biosensor immunoassay for the detection of eight sulfonamides in chicken serum

A monoclonal antibody (MAb) raised against sulfamethazine (21C7) was applied in an optical biosensor (Biacore Q) to develop a rapid biosensor immunoassay (BIA) for the detection of several sulfonamides in chicken serum. The performance of this MAb was compared with two polyclonal antibodies (PAbs) raised against sulfamethazine (Qflex sulfamethazine binding protein (SBP) and RIKILT 464b). Using these PAbs, the limits of detection (LODs) in 10 times diluted chicken serum were approximately 30 ng ml-1 and the two BIAs were found to be specific for sulfamethazine. Using MAb 21C7, the LOD for sulfamethazine in 10 times diluted chicken serum was lower (10 ng ml-1), high cross-reactivities were measured for sulfisoxazole (149¿ sulfachlorpyridazine (112¿ sulfachlorpyrazine (94¿ sulfamerazine (87¿ sulfadiazine (56¿ sulfatroxazole (56¿and sulfathiazole (50¿and low cross-reactivities (11¿25¿were measured with six other sulfonamides. Compared with the polyclonal antibodies, the MAb-based BIA resulted in a better sensitivity and was found suitable for the detection of 8 sulfonamides in 10 times diluted chicken serum with LODs between 7 and 20 ng ml-1. The total run time for each cycle was 7 min

Flow cytometric immunoassay for sulfonamides in raw milk

Sulfonamide antibiotics are applied in veterinary medicine for the treatment of microbial infections. For the detection of residues of sulfonamides in milk, a multi-sulfonamide flow cytometric immunoassay (FCI) was developed using the Luminex MultiAnalyte Profiling (xMAP) technology. In this automated FCI, a previously developed biotinylated multi-sulfonamide mutant antibody (M.3.4) was applied in combination with fluorescent beads, directly coated with a sulfathiazole derivative, and streptavidin¿phycoerythrin (SAPE) for the detection. With this FCI, at least 11 different sulfonamides could be detected (more than 50% inhibition at the 100 ng mL¿1 level) and, after an incubation of 1 h, measurements were rapid (10 s per sample). For the application with raw milk, a 96-well microplate-based filtration step was included into the protocol to remove disturbing milk fat particles. Because of differences in sensitivity towards different sulfonamides, the FCI was considered and validated as a qualitative screening assay. For sulfadoxine, the most applied sulfonamide in Dutch dairy cattle, the detection capability (CCß) wa