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The Detection of Hydrogen Peroxide and Glucose for the Electrode Modified with Ferrocene
Yi-Sheng Wang (汪乙生), 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
RESULTS AND DISCUSSION
A study was conducted to use the ferrocene to modify the carbon paste electrode. The TB
(Time Base) graphs for different operating potentials, and pH values were plotted to
determine the optimum operating conditions. The optimum weight ratio for carbon paste :
ferrocene : graphite carbon powders was carbon paste : ferrocene : graphite carbon powders
=1 : 0.3 : 0.7 . The results showed that the responding current for the carbon paste electrode
modified with ferrocene was elevated significantly. The optimum operating conditions are
-200mV operating potential, 500rpm stirring rate and in 0.05 M PBS buffer solution( pH =
7.4 ) . For the glucose biosensor, the detection limit was 0.06 mM C6H12O6 ; the linear range
was 0.06 ~ 2 mM C6H12O6 ; R2 = 0.992 and the sensitivity was 83.1 μA/ cm2．mM
C6H12O6 .
INTRODUCTION
Nowadays, diabetes is one of the top ten causes of death for the people in Taiwan .
Therefore, developing a rapid, convenient, and economical glucose biosensor for
detecting the glucose is a very 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. Because the ferrocene (Fe(C5H5)2) possesses
the excellent conductivity and catalytic characteristic, it can be used to elevate the
responding current for detection of reduction of hydrogen peroxide. A study was
conducted to use the ferrocene to modify the carbon paste electrode which was used as
the working electrode to detect the responding current of reduction of hydrogen peroxide
in the phosphate buffer solution(PBS) and then the concentration of hydrogen peroxide
could be obtained from the responding current and consequently, the sensitivity of the
glucose biosensor could be determined.
(A)
(B)
Fig 1. CV graphs for (A) carbon paste
electrode modified with ferrocene (B)
unmodified carbon paste electrode; the
range of scanning potential: -0.8～+0.8
V, scanning rate = 50 mV/s
Fig. 2 The TB graphs of carbon paste
electrode for detection of H2O2 at different
operating potentials (ferrocene : graphite
carbon powders = 3 : 7); the operating
potentials are [ (A) –300mV (B) –200mV
(C) –100mV ]
EXPERIMENTAL SECTION
Equipment
Electrochemical Analyzer (BAS 100W) was used to measure the activity of electrode by
Cyclic Voltammetry ( CV ) and Time Base ( TB ) mode ; pH meter (Metrohm 731); Constant
Temperature Thermal Bath (Wisdom BC-2DT 10L); Oven (DENG YNG) ; Electric Stirrer
(Fargo); Carbon Paste Electrode was used as the working electrode, Coiled Platinum Wire was
used as the counter electrode and Ag / AgCl was used as the reference electrode.
Chemicals and Reagents
Fig. 3 The TB graphs of carbon paste
electrode for detection of H2O2 at
different pH values of PBS buffer
solution (ferrocene : graphite carbon
powders = 3 : 7); the pH values are
[ (A) pH = 6.0 (B) pH = 7.0 (C) pH =
7.4 (D) pH = 8.0 ]
Fig. 4 TB graphs of the carbon paste
electrodes with different ratios of
carbon paste to ferrocene to graphite
carbon powders; the carbon paste to
ferrocene to graphite carbon powders
are 〔(A) 1 : 0.3 : 0.7 (B) 2 : 0.3 : 0.7
(C) 3: 0.3 : 0.7 〕
Ferrocene(Fe(C5H5)2); Hydrogen Peroxide (H2O2); D(+)-Glucose Monohydrate(C6H12O6);
Glucose Oxidase(EC 1.1.3.4, Type X-S: From Aspergillus Niger, 50000 units/mg); Graphite
Carbon Powder; Carbon Paste; Cyclohexanone(C6H10O); Nafion ; Potassium
Dihydrogenphosphate (KH2PO4); Potassium Chloride (KCl).
Procedure
(1) 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.
0.5 cm
0.05cm
Fig. 6 The TB graph of glucose biosensor
Fig.5 The TB graph of glucose
biosensor for detection of the detection
limit of glucose (ferrocene : graphite
carbon powders = 3 : 7).
7 cm
(2) 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 nakeended electric wire and dried in the oven and then we obtained the carbon paste
electrode. The surface area of the carbon paste electrode was 0.0805 cm2 .
Ferrocene
Graphite carbon powders
Mixing with carbon
paste
Coated on
the nakeended
electric wire
for detection of glucose (ferrocene : graphite
carbon powders = 3 : 7); At 30 ℃; the
operating potential = –200 mV; in 0.1 M KCl
of 5 mL 0.05 M PBS buffer solution
( pH=7.4 ); stirring rate=500 rpm; 20μL of
100mM glucose is injected per 100 seconds
CONCLUSIONS
The results showed that the responding current for the carbon paste electrode
modified with the ferrocene was elevated significantly. Because at –300mV
operating potential, it might cause the interference of the interfering substances in the
human blood, –200mV operating potential was used in this research. Also because the
pH of human blood is about 7.4, pH = 7.4 PBS buffer solution was used in this
research. The optimum operating conditions are -200mV operating potential,
500rpm stirring rate and in 0.05 M PBS buffer solution ( pH = 7.4 ) . The optimum
weight ratio for carbon paste : ferrocene : graphite carbon powders was1 : 0.3 : 0.7 .
For the glucose biosensor, the detection limit was 0.06 mM C6H12O6 ; the linear range
was 0.06 ~ 2 mM C6H12O6 ; R2 = 0.996 and the sensitivity was 83.1 μA/cm2 ．mM
C6H12O6.
(3) After the above mentioned carbon paste electrode was dried, the 2μL glucose oxidase
solution( 3mg of glucose oxidase was dissolved in 500μL PBS buffer solution ) was put
onto the surface of electrode and the electrode was dried at room temperature. Then 5μL
of 1% Nafion solution(in 95% alcohol) was dropped onto the electrode evenly and after
the electrode was dried at room temperature, we obtained the glucose biosensor.
1 % Nafion
glucose oxidase
PVC cover
REFERENCES
[1] M. A. Kim and W.-Y. Lee, “Amperometric Phenol Biosensor Based on Sol-Gel
Silicate/Nafion Composite Film,” Analytica Chimica Acta, 479, 143 (2003).
[2] L. Qian and X. Yang, “Composite Film of Carbon Nanotubes and Chitosan for
Preparation of Amperometric Hydrogen Peroxide Biosensor,” Talanta, 68,
721(2006).
[3] M. M. Musameh, R. T. Kachoosangi, L. Xiao, A. Russell and R. G. Compton, ,
“Ionic Liquid-Carbon Composite Glucose Biosensor,” Biosensors and
Bioelectronics, 24, 87 (2008).