A homemade array surface plasmon resonance (SPR)-based imaging biosensor was used to develop sensitive and fast immunoassays to determine sulfamethoxazole (SMOZ) and sulfamethazine (SMT) in buffer. Two conjugations of sulfonamide-bovine serum albumin (BSA)were separately immobilized on two different rows of the array chip with one row as reference.The immobilization was carried out in the instrument to monitor the quantity of the conjugations immobilized. The antibody mixed with the sulfonamide in the buffer was injected over the surface of the chip to get a relative response which was inversely proportional to the concentration of the sulfonamide in the PBS buffer. Two calibration curves were constructed and the limit of detection for sufamethoxazole in buffer was 3.5 ng/mL and for sulfamethazine 0.6 ng/mL. The stability and specificity of the antibody were also studied. The monoclonal antibody did not bind with BSA.