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An Analysis of the Effects of Detection of Hydrogen Peroxide for the Carbon Paste Electrode Modified with Copper Hexacyanoferrate Chia-Cheng Hsiao (蕭佳政) , Chung-Min Lien (連崇閔) , Hau Lin (林浩) Department of Chemical and Materials Engineering, Southern Taiwan University 南台科技大學化學工程與材料工程系 ABSTRACT The glucose and oxygen can be catalyzed by the glucose oxidase and the glucose is oxidized to gluconic acid and the oxygen is reduced to hydrogen peroxide. The responding current of hydrogen peroxide is detected in the phosphate buffer solution(PBS) and then the concentration of the hydrogen peroxide can be obtained and consequently, the concentration of the glucose can be determined. The Coprecipitation method was used to prepare the Copper(Ⅱ) Hexacyanoferrate(Cu(Ⅱ)HCF) in this research. The Cu(Ⅱ)HCF was used to modify the carbon paste electrode because the Cu(Ⅱ)HCF possessed the excellent catalytic characteristic and it could be used with the graphite carbon powders and carbon paste to make the carbon paste electrode to elevate the responding current of the hydrogen peroxide. A study of experimental design involving three factors (operating potential, stirring rate, and pH value of PBS) and two levels was performed to analyze the main effects and interaction effects of reaction parameters on the sensitivity of detection of hydrogen peroxide for the carbon paste electrode modified with Copper(Ⅱ) Hexacyanoferrate(Cu(Ⅱ)HCF). The results showed that the main effects of operating potential, stirring rate, and pH value of PBS were 32.735 µA/cm2．mM , 3.208 µA/cm2．mM , and -30.628 µA/cm2．mM respectively. INTRODUCTIO N ※Three Electrodes System： Working Electrode Pt Ag/AgCl Due to hydrogen peroxide is widely used in the industry and food preservation, developing a hydrogen peroxide sensor which can detect the hydrogen peroxide rapidly and conveniently is an important research subject. In recent years, diabetes has become one of the top ten causes of death for the people in Taiwan. Therefore developing a rapid and convenient glucose biosensor also has become an important research subject. Because the copper(Ⅱ) hexacyanoferrate possesses the excellent catalytic characteristic it can be used with the carbon paste and graphite carbon powders which possess the excellent conductivity to make the carbon paste electrode and to elevate the responding current of the hydrogen peroxide. The carbon paste electrode is used to detect the responding current of hydrogen peroxide in phosphate buffer solution (PBS) and the concentration of hydrogen peroxide can be determined from the responding current of hydrogen peroxide. Counter Electrode Reference Electrode N2 pH 7.4之0.05 M PBS Buffer Solution RESULTS AND DISCUSSION Fig 2. CV graphs for (A) carbon paste electrode modified with copper hexacyanoferrate (the range of scanning potential: -0.8～+0.8 V) (B) unmodified carbon paste electrode( the range of scanning potential: -0.6～+0.6 V) Temperature at 30℃ Table 1 Three factors and two levels of the factorial design Fig 1. The theory of detection of glucose for the biosensor EXPERIMENTAL Preparation of Copper(Ⅱ) Hexacyanoferrate(Cu(Ⅱ)HCF) ： 3(CuSO4．5H2O)+ 2〔K3[Fe(CN)6]〕 Cu3[Fe(CN)6]2 +3K2SO4 +15H2O Coprecipitation method： ： Stoichiometry 3 2 (mole ratio) Separation of side product Table 2 The reaction conditions of the experimental design Table 3 Algebraic signs for calculating effects in the 23 factorial design Drying at 60℃ (48 hours) CuSO4 ． 5H2O(aq) (MERCK） K3Fe(CN)6(aq)（MERCK） Cu3[Fe(CN)6]2 (aq) Preparation of the working electrode : copper(Ⅱ) hexacyanoferrate 1. Surface area of electrode=0.0805cm2 7 cm Table 4 The results of the sixteen experiments of the factorial design for detection of the sensitivity of hydrogen peroxide 0.05 cm 0.5 cm Table 5 The effects for detection of the sensitivity of hydrogen peroxide for the carbon paste electrode modified with copper hexacyanoferrate 2. Then the Copper(Ⅱ) Hexacyanoferrate powders, graphite carbon powders and carbon paste were mixed with the appropriate ratio (Copper(Ⅱ) Hexacyanoferrate : graphite carbon powders : carbon paste = 0.3 : 0.7 : 1). After the mixing was complete, the mixture was evenly coated on the nake-ended electric wire and dried in the oven and then we obtained the carbon paste electrode. The mixing of Cu(Ⅱ)HCF and carbon powders was evenly Mixing with equal amount of carbon paste 銅 芯 電 線 CONCLUSIONS The Cu(Ⅱ)HCF was used to modify the carbon paste electrode because the Cu(Ⅱ)HCF possessed the excellent catalytic characteristic and it could be used with the graphite carbon powders and carbon paste to make the carbon paste electrode [Cu(Ⅱ)HCF : graphite carbon powders = 3 : 7(weight ratio)] to elevate the responding current of the hydrogen peroxide. A study of experimental design involving three factors (operating potential, stirring rate, and pH value of PBS) and two levels was performed to analyze the main effects and interaction effects of reaction parameters on the sensitivity of detection of hydrogen peroxide for the carbon paste electrode modified with Copper(Ⅱ) Hexacyanoferrate(Cu(Ⅱ)HCF). The results showed that the main effects of operating potential, stirring rate, and pH value of PBS were 32.735 µA/cm2．mM , 3.208 µA/cm2．mM , and -30.628 µA/cm2．mM respectively. The results showed that the main effect of pH value of PBS was negative and the order of the significant level for main effects was operating potential > pH value of PBS > stirring rate. REFERENCES 1. L. Mao and K. Yamamoto,“Glucose and Choline On-Line Biosensors Based on Electropolymerized Meldola’s Blue, ”Talanta, Vol. 51, 187 (2000). 2. Y.-M. Uang and T.-C. Chou, “Criteria for Designing a Polypyrrole Glucose Biosensor by Galvanostatic Electropolymerization, ” Electroanalysis, Vol. 14, 1564 (2002). 3. M. A. Kim and W. -Y. Lee, “Amperometric Phenol Biosensor Based on Sol-Gel Silicate/Nafion Composite Film,” Analytica Chimica Acta, Vol. 479, 143 (2003).