A new method based on surface plasmon resonance (SPR) biosensors for the detection of various residues is proposed. Marking the residues with special moleculars, and the moleculars monoclonal antibody was immobilized on the sensor surface, which is covered with carboxymethyl dextran. So the direct analyte was transformed to general markers after twice incubation of samples. Bovine Serum Albumin (BSA) was used as molecular-marker in the assay, and kanamycin, melamine, ampicillin and streptomycin were marked with BSA separately. Water solution with a series concentration of the antibiotics was detected respectively in this paper. The limits of detection (LODs) reach to 50, 10, 1.25 and 10 ng/mL respectively, being much lower than maximum residue limit (MRL) accordingly. The method has solved the problem that sensors are special for the detection of residues in the competitive assay, and then the sensors will be more available. Furthermore, the method can be applied to other fields of the immunoassay, enhancing the availability of immunesensors and test papers.

Key words: surface plasmon resonance, biosensor, antibiotics residues, competitive assay, molecular mark