Abstract:In this paper， an electrochemical immunosensor for the rapid detection of ochratoxin A（OTA） was constructed by grafting OTA antibody and diazonium salt on the electrode surface. In this work， the screenprinted carbon electrodes（SPCE） were modified with diazo salt by electro-deposition. The grafted diazo film served as the bottom layer to expose the carboxyl functional groups to the electrode surface. Then carbodiimide was used to activate the carboxyl groups. The antibody and carboxyl groups were crosslinked to conduct amide bonding to realize the immobilization of the antibody. The electrochemical immunosensors were characterized by cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）. It was found that under the best working conditions， the linear detection range of the developed electrochemical immunosensor was 20-200 ng/mL（R2=0.997 0）， and the detection limit was 0.5 ng/mL. Showing excellent electrochemical performance in the detection of OTA in labeled samples， the immunosnesor was suitable for the detection of OTA in food. In addition， in the presence of interferent， the sensor was highly selective to OTA and stayed stable for 14 days. The electrochemical immunosensor is easy to construct， sensitive， fast， and stable， with low detection limits， analysis time， and cost for OTA in real samples.