The Study On Analysis Of Hydrogen Peroxide With Prussian Blue-based Electrode

The main disadvantage of Amperometric biosensors used to detect the concentration of the enzymatic substrate by H2O2 is the high overpotential needed for hydrogen peroxide oxidation(ca. >0.6V vs Ag/AgCl), at which many electroactive substances (i.e. ascorbic acid, uric acid, etc.) to be usually present in real samples could also be oxidized to give interfering signals. Recently, researchers try to overcome this problem by using of another enzyme, namely horseradish peroxidase (HRP EC 1.11.1.7). However, as a bio-enzyme, such approach also suffers from some important shortcomings such as high cost, low stability and the limited binderering of solid surface. Hexacyanoferrates, in particular Prussian Blue, can avoid this shortcomings of HRP and catalysis the reduction of H2O2 at low overpotential effectively. The study of Prussian Blue as electrochemical mediator for hydrogen peroxide has generated intense interest in last decade.The main shortcoming of the traditonal PB film modified ampeometric biosensor is the low stability of PB layer at neutral pH and alkaline pH, which confines its application actually. Many methods are employed to promote the stability of PB layer at neutral pH and alkaline pH, such as immobilizing the PB to the electrode by conductive polymers; constructing nano-structure Prussian blue including microparticles, nano-array; depositing the PB on nano-materials etc, but these approaches involve complex progresses. The pH stability seems to be dependent on the different modes of deposition of PB layer, and the structure itself is directly related to the procedure used to form PB layer. A kind of stable PB may be obtained by carefully controlling conditions. Some researchers suppose chemical deposition can led to the form of"insoluble"PB that more stable. This work suggests carbon paste electrodes modified with PB, other than glassy carbon or graphite electrodes modified by electrodeposited PB film.Two kinds of PB/carbon paste are constructed in this paper. One is to mix PB and carbon power with different bindererer, the other is chemically to deposit Prussian blue on activated graphite power, then to mix with different bindererers. The optimal composition, the electrochemical behavior and the application to detect hydrogen peroxide of the two kinds of PB/carbon paste electrode are studied. Analytical parameters such as transfers coefficient , diffusion coefficient , stability and reproducibility were as well investigated. PB/carbon paste by deposited chemically shows high stability in solution of pH=7.6. A linear range from 5×10-6~7×10-4mol/L with detection limit of 2×10-6 mol/L was obtained.