Utilizing three monoclonal antibodies in the development of an immunochromatographic assay for simultaneous detection of sulfamethazine, sulfadiazine, and sulfaquinoxaline residues in egg and chicken muscle.

A rapid and sensitive immunochromatographic assay (ICA) based on competitive format was developed and validated for simultaneous detection of sulfamethazine (SM(2)), sulfadiazine (SDZ), and sulfaquinoxaline (SQX) in chicken breast muscle and egg samples. For this purpose, three monoclonal antibodies raised against those three sulfonamides were conjugated to colloidal gold particles and applied to the conjugate pads of the test strip. The competitors of the sulfonamides (SM(2)/SDZ/SQX-bovine serum albumin conjugates) were immobilized onto a nitrocellulose membrane at three detection zones to form T(1), T(2), and T(3), respectively. With this method, the cutoff values for the three test lines were achieved at 80 µg/kg, which is lower than the maximum residue levels (MRLs) established for sulfonamides. The recoveries in negative samples spiked at concentrations of 10, 50, and 100 µg/kg ranged from 75% to 82% for egg samples and from 78% to 81% for chicken samples. The method was compared with the HPLC method by testing 180 eggs and chicken breast samples from local markets, and an agreement rate of 99.7% was obtained between the two methods.