Application of carboxyl functionalized graphene oxide as mimetic peroxidase for sensitive voltammetric detection of H2O2 with 3,3′,5,5′-tetramethylbenzidine

A sensitive electrochemical method for H2O2 determination was proposed with carboxyl functionalized graphene oxide (GO-COOH) as mimetic peroxidase and 3,3',5,5'-tetramethylbenzidine (TMB) as substrate. GO-COOH exhibited intrinsic peroxidase-like activity that could catalyze the oxidation of TMB with H2O2. The generated product exhibited a sensitive second order derivative linear sweep voltammetric reduction peak at -0.93 V (vs. Ag/AgCl) in Britton-Robinson buffer. Under the optimal conditions the reduction peak current was proportional to H2O2 concentration in the linear range from 0.006 to 0.8 mu mol L-1 with the detection limit of 1.0 nmol L-1 (3 sigma). This proposed method was further applied to determine H2O2 content in fresh milk samples with satisfactory results. (C) 2012 Elsevier B.V. All rights reserved.