Detection of Oraganophosphorus by Immobilized Wheat Esterase in Chitosan Bead

To detection of organophosphorus in spinach, the plant esterase was immobilized in magnetic chitosan bead by using glutaraldehyde as the cross-linking reagent and used for fast detection of organophosphorus pesticides. The best efficiency of immobilization could be obtained under the condition that the concentration of glutaraldehyde was 2.5%, the pH of glutaraldehyde was 5.5, the adding amount wheat esterase was 500 U, cross-linking time was 12 hours. The pesticides can be detected by the color developed during enzymatic reaction with this immobilization enzyme. The detecting sensitivity is 0.05~0.1 mg-kg^-1. The method is convenient for use and time saving.