2011_11_439de6b6

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					                        An Analysis of Variance of Detection of Hydrogen Peroxide for Carbon Paste Electrode Modified with
                                                              Copper Hexacyanoferrate

                                                                    Chia-Cheng Hsiao (蕭佳政) , Chih-Ying Wu (巫致穎) , 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 to produce the gluconic acid and hydrogen peroxide, and therefore, as the concentration of hydrogen peroxide can be determined, the concentration of
glucose can also 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 effect 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 effect of operating potential ( F = 31.755, p value <
0.05 ) and the main effect of pH value ( F = 27.798, p value < 0.05 ) were significant on the sensitivity of detection of hydrogen peroxide. At 30℃, -200 mV operating potential, 500 rpm stirring rate and in 0.05 M PBS
buffer solution ( pH = 7.4 ) , when the carbon paste electrode was modified with Copper(Ⅱ) Hexacyanoferrate (Cu(Ⅱ)HCF) [Cu(Ⅱ)HCF : graphite carbon powders : carbon paste = 0.3 :0.7 :1 ( weight ratio )] , the
detection limit was 0.02 mM H2O2 , the linear range was 0.02~2.6 mM H2O2 , R2 = 0.9945 , and the sensitivity was 121.606 µA/cm2.mM H2O2.



            INTRODUCTIO                                                                                                          ※Three Electrodes System:
                                                                                                                                                                                  Working
                                                                                                                                                                                  Electrode

                 N                                                                                                                                                 Pt
                                                                                                                                                                                                                Reference
                                                                                                                                                                                                   Ag/AgCl      Electrode
                                                                                                                                                    Counter
                                                                                                                                                    Electrode
            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                                            N2
      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 elevate the responding
                                                                                                                                                                                                         pH 7.4之0.05 M PBS
      current of the hydrogen peroxide. The carbon paste electrode is used to detect the responding current                                                                                              Buffer Solution
      of hydrogen peroxide in phosphate buffer solution (PBS) and the concentration of hydrogen peroxide
      can be determined from the responding current of hydrogen peroxide.                                                                                                                                          Temperature at
                                                                                                                            RESULTS AND DISCUSSION
                                                                                                                                                                                                                   30℃




                                                                                                                                Fig 2. CV graphs for (A) carbon paste               Table 1 Three factors and two levels of the
                                                                                                                                electrode modified with copper                      factorial design
                                                                                                                                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)
                          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:
                                                                                                                                 Table 2 The results of the sixteen experiments    Table 3 The results of analysis of variance for
            Stoichiometry 3           :         2       (mole ratio)                                                             of the factorial design ( A: Operating            the sensitivity of detection of hydrogen peroxide
                                                                                                                                 Potential(mV), B: Stirring Rate(rpm), C: pH       for the carbon paste electrode modified with
                                                                                  Separation of side product                                                                       Copper(Ⅱ) Hexacyanoferrate
                                                                                                                                 valus )

                                                                                    Drying at 60℃ (48 hours)
    CuSO4 . 5H2O(aq)          K3Fe(CN)6(aq)(MERCK)
    (MERCK)                                                            Cu3[Fe(CN)6]2 (aq)                   copper(Ⅱ)
    Preparation of the working electrode :                                                               hexacyanoferrate

    1.
                                                           Surface area of
                                                           electrode=0.0805cm2
                                         7 cm
                                                                                                                                  Table 4 The TB graphs of carbon paste            Table 5 The TB graphs of carbon paste
     0.05                                                                                                                                                                          electrodes for detection of the linear range of
    cm                                                                                                                            electrode electrodes for detection of the
                                                                                                                                  detection limit of H2O2 (Copper(Ⅱ)               H2O2 (Copper(Ⅱ) Hexacyanoferrate : graphite
               0.5 cm                                                                                                                                                              carbon powders = 3 : 7, pH= 7.4 ) .
                                                                                                                                  Hexacyanoferrate: graphite carbon powders =
    2. Then the Copper(Ⅱ) Hexacyanoferrate powders, graphite carbon powders and carbon paste were                                 3 : 7, pH= 7.4 )
    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               CONCLUSIONS
    wire and dried in the oven and then we obtained the carbon paste electrode.
                        The mixing of
                        Cu(Ⅱ)HCF
                                                                                                                                      The results showed that the responding current for the carbon paste electrode modified with
                        and carbon
                                                                                                                                Copper(Ⅱ) Hexacyanoferrate was elevated significantly. For the factorial design, the results showed
                        powders was
                                                                                                                                that the main effect of operating potential ( F = 31.755, p value < 0.05 ) and the main effect of pH
                        even.
                                                                                                                                value ( F = 27.798, p value < 0.05 ) were significant on the sensitivity. Because the pH of human
                  Mixing with                                                                                                   blood is about 7.4, pH = 7.4 was used in this research. The results showed that the optimum
                  equal amount of                                                                                               operating conditions for this research were operating potential = –200mV, stirring rate = 500 rpm,
                  carbon paste                                                                                                  and pH = 7.4. Also the results showed that at –200mV operating potential, 500 rpm stirring rate and
                                                                                                                                in 0.05M PBS buffer solution (pH=7.4), the detection limit was 0.02 mM H2O2, the linear range was
                                                                                                                                0.02~2.6 mM H2O2, R2=0.9945 and the sensitivity was 121.606 μA/cm2ּmM H2O2.
                                     銅    芯         電     線
                                                                                                                              REFERENCES


                                                                                                                               1. D. C. Montgomery, “ Design and Analysis of Experiments ,” 5th Edition, 170 (2001).
                                                                                                                               2. S. Timur, U. Anik, D. Odaci and L. Gorton, “Development of a Microbial Biosensor Based on
                                                                                                                                 Carbon Nanotube (CNT) Modified Electrodes,” Electrochemistry Communications, 9, 1810 (2007).
                                                                                                                               3. Y. Liu, J. Lei and H. Ju, “Amperometric Sensor for Hydrogen Peroxide Based on Electric Wire
                                                                                                                                  Composed of Horseradish Peroxidase and Toluidine Blue-Multiwalled Carbon Nanotubes
                                                                                                                                  Nanocomposite,” Talanta, 74, 965 (2008).

				
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