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The Effect of Stirring Rate on the Detection of Hydrogen Peroxide for Carbon Paste Electrode Modified with Meldola’s Blue
Chi-Wen Lo (羅濟玟) , 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
.
A study was conducted to use the Meldola’s Blue to modify the carbon paste electrode. Because the Meldola’s Blue 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. At 30℃, -300 mV 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 stirring rates on the responding current of detection of hydrogen peroxide. At the optimum operating conditions -300 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 Meldola’s Blue [Meldola’s Blue : carbon powders : carbon paste = 2 ：15 ：15 ( weight
ratio )] , the detection limit was 0.02 mM H2O2 , the linear range was 0.02～1.4 mM H2O2 , R2 = 0.9994 , the sensitivity was 159.39 µA/cm2．mM H2O2.
INTRODUCTION
Because hydrogen peroxide is used in the food industry for the purpose of preservation
occasionally, a rapid and convenient hydrogen peroxide sensor for detection of 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 Taiwan and 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 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. Because the Meldola’s Blue possesses the
excellent catalytic characteristic it can be used with the carbon paste and carbon powders
which possess the high conductivity to make the carbon paste electrode and elevate the
responding current of hydrogen peroxide. The responding current of hydrogen peroxide is
detected in the phosphate buffer solution (PBS), and then the sensitivity of detection of
hydrogen peroxide can be determined. A study of the TB (Time Base) graphs for the carbon
paste electrode at different stirring rates was conducted to evaluate the effect of stirring rates
on the responding current of detection of hydrogen peroxide.
EXPERIMENTAL
RESULTS AND DISCUSSION
Fig 1. CV graphs for (A) unmodified carbon
paste electrode( the range of scanning
potential: -0.8～+0.8 V) (B) carbon paste
electrode modified with Meldola’s Blue ( the
range of scanning potential: -0.8～+0.8 V)
Fig. 2The TB graphs of carbon paste
electrodes for detection of H2O2 at different
stirring rates[ (A) 300 rpm (B) 400 rpm (C)
500 rpm (D) 600 rpm ]
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 ; Oven (DENG
YNG) ; Electric Stirrer(Fargo) ; pH meter (Metrohm 731); Constant Temperature Thermal
Bath (Wisdom BC-2DT 10L); 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.
Table 1 The sensitivities, responding
currents and R2 values of different stirring
rates for the carbon paste electrode
modified with Meldola’s Blue
2. Chemicals and Reagents
Meldola’s Blue ; Hydrochloric Acid (HCl); Sodium Hydroxide (NaOH) ; Hydrogen Peroxide
(H2O2); Graphite Carbon Powder( C ); Carbon Paste; Cyclohexanone(C6H10O); Potassium
Dihydrogenphosphate (KH2PO4); Potassium Chloride (KCl).
Fig. 3 The calibration curves of different
stirring rates for the carbon paste electrode
modified with Meldola’s Blue.
3. Preparation of the Carbon Paste 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 Meldola’s Blue powders, graphite carbon powders and carbon paste were mixed
with the appropriate ratio [Meldola’s Blue : carbon powders : carbon paste = 2 ：15：15
( weight ratio )]. 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.
Fig. 4 The TB graphs of carbon paste
electrode for determining the
detection limit of H2O2 [Meldola’s Blue :
carbon powders : carbon paste =
2 ：15：15 ( weight ratio )]
Fig. 5 The TB graphs of carbon paste
electrode for determining the linear
range of H2O2 [Meldola’s Blue : carbon
powders : carbon paste = 2 ：15：15
( weight ratio )]
CONCLUSIONS
The results showed that the responding current for the carbon paste electrode modified
with the Meldola’s Blue was elevated significantly. The TB (Time Base ) graphs at different
stirring rates were plotted to evaluate the effect of stirring rate on the responding current of
detection of hydrogen peroxide and determine the optimum operating conditions. The
results showed that at the optimum operating conditions –300mV operating potential,
500rpm stirring rate and in 0.05M phosphate buffer solution(pH=7.4), the detection limit
was 0.02 mM, the linear range was 0.02~1.4 mM H2O2 , R2=0.9994 and the sensitivity was
159.39 μA/cm2ּmM H2O2 .
Meldola’s Blue
REFERENCES
Mixing with Carbon Paste
Carbon Powders
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DEPARTMENT OF CHEMICAL AND MATERIALS ENGINEERING, SOUTHERN TAIWAN UNIVERSITY