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The Detection of Glucose for the Carbon Paste Electrode Modified with
Ruthenium Hexacyanoferrate
Kuo-Hsiang Liao (廖國翔) , 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：
Both the hydrogen peroxide sensor and glucose biosensor are important research subjects. A study was conducted to use the ruthenium hexacyanoferrate(Ⅱ) 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 PBS buffer solution( pH = 7.4 )and the sensitivity of detection of hydrogen peroxide was determined from the responding current and consequently, the concentration of the
glucose could be determined. The TB (Time Base) graphs for different operating potentials, stirring rates, and pH values were plotted to determine the optimum operating conditions. The results showed that the responding current for the
carbon paste electrode modified with the ruthenium hexacyanoferrate(Ⅱ) was elevated significantly. At 30℃ , -0.2V operating potential, 600rpm stirring rate and in 0.05 M PBS buffer solution( pH = 7.4 ), when the carbon paste electrode was
modified with the ruthenium hexacyanoferrate(Ⅱ) [ruthenium hexacyanoferrate(Ⅱ) : graphite carbon powders = 3 : 7 ( weight ratio )] , the detection limit was 0.02 mM H2O2 , the linear range was 0.02～2.7 mM H2O2, R2=0.9996, and the
sensitivity was 661.8 μA/cm2ּmM H2O2 . For the glucose biosensor, the detection limit was 0.02 mM C6H12O6 , the linear range was 0.02~2.56 mM C6H12O6 (R2=0.999), and the sensitivity was 4.11 µA/cm2．mM C6H12O6. The optimum operating
conditions are -200mV operating potential, 600rpm stirring rate and in 0.05 M PBS buffer solution( pH = 7.4 ) [ruthenium hexacyanoferrate(Ⅱ) : graphite carbon powders = 3 : 7 ( weight ratio )] .
INTRODUCTION ：
(
)
A study was conducted to use the ruthenium hexacyanoferrate(Ⅱ) to modify the carbon paste
electrode which was used as the working electrodes 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
concentration of the glucose could be determined. At 30℃, the TB (Time Base) graphs for the
carbon paste electrode modified with ruthenium hexacyanoferrate [ruthenium
hexacyanoferrate(Ⅱ) : graphite carbon powders = 3 : 7 ( weight ratio )] were plotted to evaluate
the effect of reaction parameters on the responding current of detection of hydrogen peroxide.
After the optimum conditions were determined, the carbon paste electrode was used to
determine the sensitivity of detection of hydrogen peroxide and glucose.
EXPERIMENTAL SECTION：
( )
Preparation of Ruthenium
Hexacyanoferrate ：
30 mM Potassium
Hexacyanoferrate 5 mL
Drying
Centrifuging
Repeat Centrifuging
Ruthenium
Hexacyanoferrate
Powders
Three Times
Fig 1. CV graphs for (A) carbon paste electrode
modified with ruthenium 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. 2 The TB graphs of carbon paste electrode for
detection of H2O2 at different operating potentials
( ruthenium hexacyanoferrate : graphite carbon
powders = 3 : 7); the operating potentials are
[ (A) –50mV (B) –100mV (C) –200mV (D) –300mV ]
3 mM Ruthenium Chloride
Hydrate 50 mL
Preparation of Working Electrode：
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.
7 cm
0.05 cm
0.5 cm
2. Then the ruthenium hexacyanoferrate(Ⅱ) powders, carbon powders and carbon paste were
mixed with the appropriate ratio.
adding carbon paste
ruthenium
hexacyanoferrate
Fig. 3 The TB graphs of carbon paste electrode for
detection of H2O2 at different stirring rates
( ruthenium hexacyanoferrate : graphite carbon
powders = 3 : 7); the stirring rates are [ (A) 300rpm
(B) 400rpm (C) 500rpm (D) 600rpm(E) 700rpm]
Fig. 4 The TB graphs of carbon paste electrode for
detection of H2O2 at different pH values of PBS
buffer solution ( ruthenium hexacyanoferrate :
graphite carbon powders = 3 : 7); the pH values are
[ (A) pH = 4 (B) pH = 5 (C) pH = 6 (D) pH = 7 (E)
pH = 7.4 (F) pH = 8 ]
( appropriate ratio )
carbon
powder
A
powder
appropriate A
powder
3. 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.
4. After the above mentioned carbon paste electrode was dried, the 3μL
glucose oxidase solution( 3mg of glucose oxidase was dissolved in 200μL 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.
Fig. 5 The TB graph of glucose biosensor
for detection of the detection limit of
glucose (ruthenium hexacyanoferrate(Ⅱ) :
graphite carbon powders = 3 : 7).
Fig. 6 The TB graphs of glucose biosensor for
detection of glucose ( ruthenium
hexacyanoferrate(Ⅱ) : carbon powders = 3 : 7); At
30 ℃; the operating potential = –200 m V; in 0.1 M
KCl of 5 mL 0.05 M PBS buffer solution ( pH=7.4 );
stirring rate=600 rpm; 16μL of 100mM glucose is
injected per 100 seconds
CONCLUSIONS ：The results showed that the optimum weight ratio for carbon paste : ruthenium
hexacyanoferrate(Ⅱ) : carbon powders was 1 : 0.3 : 0.7 . At 30℃ , -200mV operating potential,
600rpm stirring rate and in 0.05 M PBS buffer solution( pH = 7.4 ), when the carbon paste electrode
was modified with the ruthenium hexacyanoferrate(Ⅱ) , the detection limit was 0.02 mM H2O2 , the
linear range was 0.02～2.7 mM H2O2 , R2=0.9996, and the sensitivity was 661.8 μA/cm2ּmM H2O2 . For
the glucose biosensor, the detection limit was 0.02 mM C6H12O6 , the linear range was 0.02~2.56 mM
C6H12O6 (R2=0.999), and the sensitivity was 4.11 µA/cm2．mM C6H12O6 . The optimum operating
conditions are -200mV operating potential, 600rpm stirring rate and in 0.05 M PBS buffer solution( pH
= 7.4 ) .
Nafion
Glucose Oxidase
PVC cover
REFERENCES ：
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Film,” Analytica Chimica Acta, 479, 143 (2003).
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Assembly for Biosensor Applications,” Biomaterials, 28, 3408 (2007).
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Bioelectronics, 24, 819 (2008).
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