The fast and selective determination of hydrogen peroxide (H2O2) is of importance not only because of strong interest to this widely applied analyte but also because of the development of enzymatic biosensors for glucose or other metabolites where the sensor for H2O2 can be used as the transducer. We report here electrocatalytical amperometric sensor for detection of H2O2. The sensor consists of a gold electrode covered by self-assembled monolayer (SAM) with immobilized p-benzoquinone. To provide highly stable immobilization of p-benzoquinone at the distance of effective electron tunneling, a new anchor compound - 1,3-dimercaptopropan-2-ol – was synthesized and used for the preparation of the SAM. Due to two thiol groups binding gold surface this compound provides a high stability of the SAM. The surface concentration of p-benzoquinone obtained from cyclic voltammetry is 2.5 ± 0.2 × 10−10 mol·cm−2. Cyclic voltammetry and chronoamperometry experiments proved that the immobilized benzoquinone exhibited high electrocatalytic activity towards the decomposition of H2O2. Depending on the used potential range, different sensing modes can be realized. For example, one can measure electrochemical response due to the oxidation of H2O2 at anodic potentials or due to the reduction of oxygen formed during oxidative decomposition of H2O2. Also amperometric response at fixed potential of +0.4 V vs. Ag/AgCl corresponding to the oxidation of benzoquinone to hydroquinone was studied. The sensor exhibited a linear response over a concentration range of 0.1–2 mM with a low detection limit of 4.24 µM. The reproducibility of three different electrodes prepared was examined at the H2O2 concentration range from 0.1 till 3 mM, which resulted in a relative standard deviation below 4.2%.
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