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The Stirring Rate on the Sensitivity of Detection of Hydrogen Peroxide for the Carbon Paste
Electrode Modified with Copper Hexacyanoferrate
Chia-Cheng Hsiao (蕭佳政) , Ting-Li Lin (林庭立) , 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
Because sometimes hydrogen peroxide is used in the food industry for the purpose of preservation , a rapid and convenient sensor for detecting the hydrogen peroxide is an important research subject. A study was
conducted to use the Coprecipitation method to prepare the Copper(Ⅱ) Hexacyanoferrate(Cu(Ⅱ)HCF) [Cu(Ⅱ)HCF : graphite carbon powders = 3 : 7(weight ratio)]. 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 at different operating conditions. At 30℃, -0.2V operating potential, and in 0.05 M phosphate buffer solution (PBS), the TB (Time Base) graphs for the carbon paste electrode at different
stirring rates were plotted to evaluate the effect of the stirring rate on the responding current of detection of hydrogen peroxide. The results showed that at the optimum operating conditions -0.2 V operating potential,
500rpm stirring rate and in 0.05M phosphate 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.
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℃
Fig. 3 The TB graphs of carbon paste
electrodes for detection of H2O2 at
different stirring rates(Copper(Ⅱ)
Hexacyanoferrate : graphite carbon powders =
3 : 7); the stirring rates are [ (A) 200 rpm (B)
300 rpm (C) 400 rpm (D) 500 rpm (E) 600 rpm ]
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
Fig. 4 The calibration curves of different
stirring rates for the carbon paste electrode
modified with copper hexacyanoferrate [ (A)
200 rpm (B) 300 rpm (C) 400 rpm (D) 500 rpm
(E) 600 rpm ]
Table 1 The sensitivities , responding currents
and R2 values of different stirring rates for the
carbon paste electrode modified with copper
hexacyanoferrate
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
0.05
cm
0.5 cm
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.
Fig. 5 The TB graphs of carbon paste electrode
electrodes for detection of H2O2 (pH=7.4)
Fig. 6 The TB graphs of carbon paste electrodes
for detection of H2O2 ; 10μL of 100mM H2O2 is
injected per 100 seconds (pH=7.4)
CONCLUSIONS
The mixing of
Cu(Ⅱ)HCF
and carbon
powders was
evenly
Mixing with
equal amount of
carbon paste
銅
芯
電
線
The results showed that the responding current for the carbon paste electrode modified with the
Copper(Ⅱ) Hexacyanoferrate was elevated significantly. The TB (Time Base ) graphs at different
stirring rates were plotted to evaluate the effect of the stirring rate on the responding current of
detection of hydrogen peroxide and determine the optimum operating conditions. Because when the
stirring rate was 600 rpm, it caused the electrode to be unstable, 500 rpm stirring rate was used in
this study and because the pH of human blood is about 7.4, phosphate buffer solution pH=7.4 was
used in this study. At –0.2V operating potential, 500rpm stirring rate and in 0.05M phosphate 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. This research can be further applied to
the glucose biosensor in the future.
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).