An Analysis of the Effects of Detection of Hydrogen Peroxide for the Carbon Paste Electrode Modified with Ferrocene Pao-Tsai Kuo ( 郭寶財 ), 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 A study was conducted to use the ferrocene to modify the carbon paste electrode. Because the ferrocene(Fe(C 5 H 5 ) 2 ) possesses the excellent catalytic characteristic, it can be used with the graphite carbon powders which possesses the excellent conductivity to make the carbon paste electrode and to elevate the responding current of 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. A study of factorial 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 ferrocene. The results showed that the main effects of operating potential, stirring rate, and pH value of PBS were µA/cm 2 ． mM, µA/cm 2 ． mM, and µA/cm 2 ． mM respectively. The operating potential-stirring rate interaction effect was µA/cm 2 ． mM, operating potential-pH value of PBS interaction effect was µA/cm 2 ． mM, stirring rate- pH value of PBS interaction effect was 4.14 µA/cm 2 ． mM, and operating potential-stirring rate-pH value of PBS interaction effect was µA/cm 2 ． mM. INTRODUCTION Because hydrogen peroxide is widely used in the food industry for the purpose of preservation nowadays, a rapid and convenient sensor for detecting the hydrogen peroxide is an important research subject. In recent years, diabetes has become one of the top ten causes of death for the people in our country. Therefore developing a rapid and convenient glucose biosensor also has become an important research subject. 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 electrode releases the electrons at the reductive potential and converts the mediator to the reductive state. Then the mediator at the reductive state releases the electrons to reduce the hydrogen peroxide to water and consequently the mediator at the reductive state is converted to the oxidizing state. The responding current for detecting the hydrogen peroxide is used to measure the amount of hydrogen peroxide and consequently determine the concentration of the glucose. Therefore, the detecting technique for the hydrogen peroxide is an important research subject. Because the ferrocene(Fe(C 5 H 5 ) 2 ) possesses the excellent catalytic characteristic, it can be used with the graphite carbon powders which possess the excellent conductivity to make the carbon paste electrode and to elevate the responding current of 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. At 30 ℃, and in 0.05 M phosphate buffer solution (PBS), the CV graphs for (A) carbon paste electrode modified with ferrocene ( the range of scanning potential: -0.8 ～ +0.8 V) and (B) unmodified carbon paste electrode( the range of scanning potential: -0.8 ～ +0.8 V) were plotted to show that the responding current for the carbon paste electrode modified with ferrocene was elevated significantly. EXPERIMENTAL 1. Equipment Electrochemical Analyzer (CHI 401A, CH Instruments, Inc) was used to measure the activity of electrode by Cyclic Voltammetry ( CV ) and Time Base ( TB ) mode ; Electric Stirrer(Fargo) ; pH meter (Metrohm 731); Constant Temperature Thermal Bath (Wisdom BC-2DT 10L); Oven (DENG YNG) ; Carbon Paste Electrode was used as the working electrodes, Coiled Platinum Wire was used as the counter electrode and Ag / AgCl was used as the reference electrode. 2. Chemicals and Reagents Ferrocene ; Hydrochloric Acid (HCl); Sodium Hydroxide (NaOH) ; Hydrogen Peroxide (H 2 O 2 ); Graphite Carbon Powder( C ); Carbon Paste; Cyclohexanone(C 6 H 10 O); Potassium Dihydrogenphosphate (KH 2 PO 4 ); Potassium Chloride (KCl). 3. Preparation of the Carbon Paste Electrode Take one section of 7 cm electric wire with 0.05 cm inside diameter. After depriving the coating 0.5 cm length from both ends, the nake-ended wire was washed, dried and ready for use. Then the ferrocene powders, graphite carbon powders and carbon paste were mixed with the appropriate ratio (ferrocene : 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. 7 cm 0.5 cm 0.05 cm Ferrocene Graphite carbon powders Mixing with equal amount of carbon paste DEPARTMENT OF CHEMICAL AND MATERIALS ENGINEERING, SOUTHERN TAIWAN UNIVERSITY RESULTS CONCLUSIONS The experimental results showed that the responding current for the carbon paste electrode modified with ferrocene was elevated significantly. A study of factorial 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 ferrocene. The results showed that the main effects of operating potential, stirring rate, and pH value of PBS were µA/cm 2 ． mM, µA/cm 2 ． mM, and µA/cm 2 ． mM respectively. The operating potential-stirring rate interaction effect was µA/cm 2 ． mM, operating potential-pH value of PBS interaction effect was µA/cm 2 ． mM, stirring rate-pH value of PBS interaction effect was 4.14 µA/cm 2 ． mM, and operating potential-stirring rate-pH value of PBS interaction effect was µA/cm 2 ． mM. The results showed that the order of the significant level for main effects was operating potential > pH value of PBS > stirring rate and all the main effects were positive. 1. L. Charpentier and N. El Murr, “Amperometric Determination of Cholesterol in Serum with Use of a Renewable Surface Peroxidase Electrode,” Analytica Chimica Acta, Vol. 318, 83 (1995). 2. R. Nagata, S. A. Clark, K. Yokoyama, E. Tamiya and K. Isao, “Amperometric Glucose Biosensor Manufactured by a Printing Technique” Analytica Chimica Acta, Vol. 304, 157(1995). 3. H. Liu, H. Li, T. Ying, K. Sun, Y. Qin, and D. Qi, “Amperometric Biosensor Snesitive to Glucose and Lactose Based on Co-Immobilization of Ferrocene, Glucose Oxidase, β-Galactosidase and Mutarotase in β-cyclodextrin Polymer,” Analytica Chimica Acta, Vol. 358, 137( 1998) 4. Y.-M. Uang and T.-C. Chou, “Fabrication of Glucose Oxidase/Polypyrrole Biosensor by Galvanostatic Method in Various pH Aqueous Solutions,” Biosensors and Bioelectronics, Vol. 19, 141(2003). REFERENCES (B) (A) Fig 1. CV graphs for (A) carbon paste electrode modified with ferrocene ( the range of scanning potential: -0.8 ～ +0.8 V) (B) unmodified carbon paste electrode( the range of scanning potential: -0.8 ～ +0.8 V ) Table 1 Three factors and two levels of the factorial design Table 2 The reaction conditions of the factorial design Table 3 Algebraic signs for calculating effects in the 2 3 factorial design Table 4 The results of the sixteen experiments of the factorial design for detection of the sensitivity of hydrogen peroxide Table 5 The effects for detection of the sensitivity of hydrogen peroxide for the carbon paste electrode modified with ferrocene