Development of a sensitive monoclonal antibody-based ELISA for the detection of sulfamethazine in cow milk, honey, and swine urine.

A specific monoclonal antibody (MAb) against sulfamethazine was produced with hybridoma technology. This assay shows very high sensitivity with IC50 of 0.4 ng/mL and LOD of 0.05 ng/mL when it was run in 0.02 mol/L PBS (pH 7.5). This MAb has shown high specificity to sulfamethazine, with little cross reactivity for sulfamerazine (5.27%) and sulfadimethoxypyrimidine (1.12%) and very low cross reactivity values for the other test compounds (≤0.1%). Sulfamethazine was spiked in milk, honey, and swine urine. After a simple extraction procedure the extracts at appropriate dilution were analyzed by ELISA. Satisfactory results were obtained by this assay, with average recoveries of 95-116% and coefficients of variation (CVs) of 5-9%. These results suggests that the MAb-based ELISA will be a feasible quantitative/screening method for sulfamethazine residue in real samples.