▎ 摘　　要

NOVELTY - A co-immobilized enzyme electrode preparing method involves mixing graphene oxide, concentrated sulfuric acid and nitric acid, and concentrated hydrochloric acid, filtering and washing to give a carboxylated graphene oxide. The resulting carboxylated graphene oxide is added with thionyl chloride and N,N-dimethylformamide to give graphene oxide chloride. The oxide chloride obtained is mixed with ethylenediamine. The obtained graphene dispersion is reacted with glutaraldehyde to give solution system followed by adding mixed liquid of tyrosinase and peroxidase solution, and drying. USE - Method for preparing co-immobilized enzyme electrode that is utilized for detecting hydroquinone and catechol. ADVANTAGE - The electrode can detect hydroquinone and catechol with high selectivity and sensitivity, low detection limit, in simple, and fast manner. DETAILED DESCRIPTION - A co-immobilized enzyme electrode preparing method involves mixing graphene oxide, concentrated sulfuric acid and nitric acid for 1-2 hours, and concentrated hydrochloric acid ultrasound for 1-2 hours, filtering and washing with deionized water, drying at room temperature to give a carboxylated graphene oxide, where the weight ratio of graphene oxide mixed with acid is 5-15 mg, and the concentrated sulfuric acid and nitric acid id 2: 1-4: 1. The resulting carboxylated graphene oxide is added with thionyl chloride and N, N- dimethylformamide, a mixed solution of the amide at 60-80 degrees C in a water bath, stirred for 12-48 hours, by filtration, washed with anhydrous tetrahydrofuran at room temperature and dried in vacuum to give graphene oxide chloride, where the ratio of carboxylated graphene oxide mixed with solution is 5-15 mg: 50-150 mL, and the chloride sulfoxide and N, N- dimethylformamide is10: 1-30: 1. The oxide chloride obtained is mixed with ethylenediamine, stirred for 12-48 hours, filtered, dried at room temperature under vacuum to give amide graphene oxide, where the ratio of graphene oxide-chloride with ethylenediamine is 5-15 mg: 20-60 mL. The amide is mixed buffer solution to adjust pH 6-7, ultrasonic dispersion is performed for 20-40 minutes to obtain l-3 mg/mL graphene dispersion. 100-300 mu l graphene dispersion is taken, reacted with 2-10% glutaraldehyde in an ultrasonic shaker for 20-40 minutes after shaking for 1-3 hours, to give a solution system followed by adding 2-10 mg/mL mixed liquid of tyrosinase and peroxidase solution to the resultant solution system, reacting for 1-3 hours to obtain co-immobilized enzyme solution, where the solvent is a buffer solution, pH 6.0-7.0, applying co-immobilized enzyme on the glassy carbon electrode to activation treatment, dispensing volume of 5-20 mu L, drying at 4 degrees C, coating 0.2-1.0% chitosan solution on a glassy carbon electrode, after drying, sprinkling terephthalic and phthalic on co-immobilized enzyme electrode, and drying to obtain finished product.