AN AMPEROMETRIC IMMUNOSENSOR FOR COCAINE

A novel reusable amperometric immunosensor was developed for the deter mination of cocaine by co-immobilizing horseradish peroxidase (POD) an d benzoylecgonine-antibody on a chemically activated affinity membrane which is mounted over the tip of an oxygen electrode. The enzymatic e lectrocatalytic current response to the respective substrate is inhibi ted by the association of the antigen to the co-immobilized antibody. The calibration plot for cocaine is linear in the concentration range of 1x10(-7)-1x10(-5) M. The sensor can be regenerated to facilitate se veral assays by washing with dilute hydrochloric acid solution, and is stable for over 25 days. The advantages of the sensor include rapid-r esponse, simple analysis methodology and high selectivity. The optimal conditions of immobilization and pH have been studied. The inhibition of enzymatic activity was confirmed by luminescence measurement utili zing the luminol-H2O2-POD system.