Development of a Monoclonal Antibody‐based ELISA for Detection of Sulfamethazine and N 4 −acetyl Sulfamethazine in Chicken Breast Muscle Tissue

An anti‐sulfamethazine monoclonal antibody was developed in a BALB/c mouse immunized with sulfamethazine (SM 2 ) ‐human serum albumin (HSA). Using this monoclonal antibody, an indirect competitive enzyme‐linked immunosorbent assay (cELISA) was developed to detect SM 2 and its metabolites in chicken breast muscle tissue. The 50% inhibition value (IC 50 ) was 9.3 ng/mL. When SM 2 was spiked at levels of 20 to 200 ng/g, recoveries ranged from 81.3% to 104.2% with coefficients of variation (CVs) of 4.3% to 19.3%. The metabolite N 4 −acetyl SM 2 was also evaluated by the same assay. When it was fortified atlevels of 20 to 200 ng/g, recoveries ranged from 80.4% to 100.8% with CVs of 3.0% to 14.2%. The results were confirmed with analysis by high‐performance liquid chromatography (HPLC). In an actual residue study, the results obtained by cELISA did not correlate well with those obtained by HPLC ( P < 0.05). This might be due to the coextraction of cross‐reactive SM 2 ‐related residues that were not quantified by the HPLC method. The study indicated that the presence of residues should be anticipated when considering the maximum residue limit of SM 2 residue.