▎ 摘　　要

NOVELTY - An electrochemical sensor preparing method involves dispersing graphene oxide in ethanol by adding silane and EDTA reagent and stirring, and centrifuging to obtain EDTA-graphene oxide composite material. The composite material is dispersed in water ultrasonically for 30-50 minutes, added with hydrazine hydrate to carry out reduction, centrifuged and dried to obtain EDTA-graphene, which is prepared into aqueous solution, coating a glassy carbon electrode by dropping 5 mu l the solution, and drying to obtain an electrochemical sensor. USE - Method for preparing electrochemical sensor that is utilized for selective determination of mercury and copper ions content (claimed). ADVANTAGE - The method enables preparing the electrochemical sensor with better selectivity. DETAILED DESCRIPTION - An electrochemical sensor preparing method involves dispersing 10 mg graphene oxide in 50-70 ml ethanol by adding 5 ml 1.0% silane and EDTA reagent and stirring at 65 degrees C for 10-12 hours, and centrifuging to obtain EDTA-graphene oxide composite material. The composite material is dispersed in 30-50 ml water ultrasonically for 30-50 minutes, added with 0.2-0.4 ml hydrazine hydrate to carry out reduction at 85 degrees C under relux for 8-10 hours, centrifuged and dried to obtain EDTA-graphene, which is prepared into 1 mg/ml aqueous solution, coating a glassy carbon electrode by dropping 5 mu l the solution, and drying to obtain an electrochemical sensor. An INDEPENDENT CLAIM is also included for an electrochemical sensor prepared by the method.