• Analytical Science and Technology
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• v.19 no.1
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• pp.58-64
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• 2006

A mugwort-tissue-based modified carbon paste electrode was constructed for the amperometric detection of hydrogen peroxide and its electrochemical properties are described. Especially the amperometric signal was very stable and bigger than any other enzyme electrode studied in this lab. The effect of tissue composition on the response was linear within the wide range of experiment and the linearity of Lineweaver-Burk plot showed that the sensing process of the biosensor is by enzymatic catalysis. And pH dependent current profile connoted that two isozymes are active in this system.

• Journal of the Korean Chemical Society
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• v.44 no.4
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• pp.376-379
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• 2000

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.178-179
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• 2002

최근에 화학, 임상병리, 환경 감시 등의 분야에서 산소센서의 수요가 점차 증가하고 있다. 이러한 산소 센서 중에 가장 많이 쓰이는 방식은 산화물 전극을 사용하는 amperometric 방법이지만 이 방법들은 장기간에 걸쳐 볼 때 산화물 전극의 오염, 외부 자기장의 간섭 등의 제점 때문에 산소를 측정하는데 많은 어려움이 있다. (1) 따라서 최근에는 빛과 유기염료를 통하여 산소의 농도가 증가할수록 세기가 quenching이 되는 원리를 이용한 산소센서의 연구가 이루어졌다. (중략)

• 대한한약학회:학술대회논문집
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• 2007.11a
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• pp.182-182
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• 2007

• Bulletin of the Korean Chemical Society
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• v.22 no.8
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• pp.816-820
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• 2001

A new copper hexacyanoferrate modified electrode was constructed by mechanical immobilization. The modified electrode was characterised by cyclic voltammetric experiments. Electrocatalytic oxidation of glutathione was effective at the modified electrode at a significantly reduced overpotential and at broader pH range. The modified electrode shows a stable and linear response in the concentration range of 9 ${\times}$10-5 to 9.9 ${\times}$10-4M with a correlation coefficient of 0.9995. The modified electrode exhibits excellent stability, reproducibility and rapid response and can be used in flow injection analysis for the determination of glutathione.

• Analytical Science and Technology
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• v.29 no.1
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• pp.35-42
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• 2016

A new nano-composite carbon ink for the development of disposable dopamine (DA) biosensors based on screen-printed carbon electrodes (SPCEs) is introduced. The method developed uses SPCEs coupled with a tyrosinase modified nano-composite carbon ink. The ink was prepared by an “in-house” procedure with reduced graphene oxide (rGO), Pt nanoparticles (PtNP), and carbon materials such as carbon black and graphite. The rGO-PtNP carbon composite ink was used to print the working electrodes of the SPCEs and the reference counter electrodes were printed by using a commercial Ag/AgCl ink. After the construction of nano-composite SPCEs, tyrosinase was immobilized onto the working electrodes by using a biocompatible matrix, chitosan. The composite of nano-materials was characterized by X-ray photoelectron spectroscopy (XPS) and the performance characteristics of the sensors were evaluated by using voltammetric and amperometric techniques. The cyclic voltammetry results indicated that the sensors prepared with the rGO-PtNP-carbon composite ink revealed a significant improvement in electro-catalytic activity to DA compared with the results obtained from bare or only PtNP embedded carbon inks. Optimum experimental parameters such as pH and operating potential were evaluated and calibration curves for dopamine were constructed with the results obtained from a series of amperometric detections at −0.1 V vs. Ag/AgCl. The limit of detection was found to be 14 nM in a linear range of 10 nM to 100 µM of DA, and the sensor’s sensitivity was calculated to be 0.4 µAµM⁻¹cm⁻².

• Journal of Sensor Science and Technology
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• v.9 no.3
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• pp.203-207
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• 2000

The sensitivity of ISFET glucose sensor is improved by employing amperometric actuation method. However, this method takes long time to recover the primary output voltage after measurement because of slow migration of the hydrogen ion between internal and external sensing membranes. Consequently, such a recovery-time delaying problem is one of obstacles to a practical use. In this paper, a new method is proposed to control the concentration of hydrogen ion in internal membrane, which applies a reduction potential to the working electrode for supplying hydroxide ion. Experimental results show that the recovery-time was reduced within 2 minute against decades minute of conventional method.

• Analytical Science and Technology
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• v.10 no.2
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• pp.131-138
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• 1997

Supercritical Fluid Chromatography(SFC) has become a technique for solving problems that are difficult to be monitored by other chromatographic methods. However, the most widely used fluid, is no more polar than hexane. Polar samples which are difficult to be analyzed with pure supercritical $CO_2$ because of their high polarity can be separated by adding polar modifiers to supercritical $CO_2$. In this paper, a new method for monitoring the mobile phase composition in modified supercritical fluid chromatography was developed. The amount of water dissolved in supercritical $CO_2$ was measured by amperometric microsensor which is made of thin film of perfluorosulfonate ionomer(PFSI). The amount of water dissolved in supercritical $CO_2$ stayed constant for a much longer time than with a saturator column. With this new mixing device, we could get good resolutions for vitamins which are difficult to separate with pure $CO_2$.

• Analytical Science and Technology
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• v.10 no.5
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• pp.350-356
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• 1997

Supercritical Fluid Chromatography(SFC) has been developed as an analytical technique for the compounds that is difficult to analyze by conventional chromatography. Since supercritical fluid $CO_2$ is difficult to elute solutes with high polarity, modified supercritical $CO_2$, was used as a mobile phase. In conventional method, silica column which is saturated with modifier was used. However, with this method, we can not control the quantity of modifier. In this paper, we developed a new method which can control quantity of modifier mixed in supercritical fluid $CO_2$. The quantity of $H_2O$ mixed was measured with amperometric microsensor which was made by perflurosulfonate ionomer(PFSI) film. we have also obtained a good supercritical fluid chromatogram of PAH mixture by use of a modifier composition programming method.

• Journal of the Korean Chemical Society
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• v.48 no.5
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• pp.491-498
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• 2004

The response characteristics of the bioelectrode developed by the co-immobilization of black goat liver tissue and ferrocene in a carbon paste matrix for the amperometric determination of hydrogen peroxide were evaluated. In the range of electrode potential examined ($-0.3{\sim}+0.0\;V$ vs. Ag/AgCl), the response time was relatively short (t95%=12 s) and it responded in the wide range of pH. The detection limit was 2.25${\times)10^{-6}M$ and a relative standard deviation of the measurements which were repeated 15 times using 1.0${\times}10^{-2 }$M hydrogen peroxide was 1.87%. The bioelectrode sensitivity decreased to 50% of the original value in 19 days of continuous use.