• Bulletin of the Korean Chemical Society
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• v.18 no.3
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• pp.316-318
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• 1997

A general and universal detection method, which can be used in high performance liquid chromatography (HPLC) and flow injection analysis (FIA) system for the determination of any metal ions complexing with ethylenediaminetetraacetic acid (EDTA), is demonstrated. Pulsed amperometric detection scheme is applied in a flow-through thin layer electrochemical cell at an Au working electrode. Fluctuation of peak current level at the same flow rate of carrier solution is minimized at this solid working electrode, whereas not at a dropping mercury electrode. Removal of dissolved oxygen can be omitted with this detection method, which is a required step for cathodic detection methods. Also, a group of metal ions can be determined selectively and indirectly with this detection scheme.

• Journal of Electrochemical Science and Technology
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• v.14 no.3
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• pp.215-221
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• 2023

A rapid and environment-friendly electrochemical sensor to determine the chemical oxygen demand (COD) has been developed. The boron-doped diamond (BDD) thin-film electrode is employed as the anode, which fully oxidizes organic pollutants and provides a current response in proportion to the COD values of the sample solution. The BDD-based amperometric COD sensor is optimized in terms of the applied potential and the solution pH. At the optimized conditions, the COD sensor exhibits a linear range of 0 to 80 mg/L and the detection limit of 1.1 mg/L. Using a set of model organic compounds, the electrochemical COD sensor is compared with the conventional dichromate COD method. The result shows an excellent correlation between the two methods.

• Analytical Science and Technology
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• v.27 no.4
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• pp.181-186
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• 2014

• 대한한약학회:학술대회논문집
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• 2007.11a
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• pp.175-175
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• 2007

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.94.1-94
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• 2002

• Bulletin of the Korean Chemical Society
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• v.12 no.1
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• pp.10-12
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• 1991

• Bulletin of the Korean Chemical Society
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• v.26 no.9
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• pp.1403-1409
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• 2005

A sensitive and selective electrochemical method was developed for the amperometric determination of ascorbic acid (AA) at a glassy carbon electrode (GCE) modified with single-wall carbon nanotubesdihexadecyl hydrogen phosphate (SWNT-DHP) composite film. The SWNT-DHP composite film modified GCE was characterized with SEM. The SWNT-DHP composite film modified GCE exhibited excellent electrocatalytic behaviors toward the oxidation of AA. Compared with the bare GCE, the oxidation current of AA increased greatly and the oxidation peak potential of AA shifted negatively to about -0.018 V (vs. SCE) at the SWNT-DHP composite film modified GCE. The experimental parameters, which influence the oxidation current of AA, were optimized. Under the optimal conditions, the amperometric measurements were performed at a applied potential of -0.015 V and a linear response of AA was obtained in the range from 4 ${\times}$ $10^{-7}$ to 1 ${\times}$ $10^{-4}$ mol $L^{-1}$ and with a limit of detect (LOD) of 1.5 ${\times}$ $10^{-7}$ mol $L^{-1}$. The interferences study showed that the SWNT-DHP composite film modified GCE exhibited good sensitivity and excellent selectivity in the presence of high concentration uric acid and dopamine. The proposed procedure was successfully applied to detect AA in human urine samples with satisfactory results.

• Journal of Ginseng Research
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• v.44 no.4
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• pp.563-569
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• 2020

Background: White ginseng consists of the roots and rhizomes of the Panax species, and red ginseng is made by steaming and drying white ginseng. While red ginseng has both polar and nonpolar ginsenosides, previous studies showed white ginseng to have only polar ginsenosides. Because nonpolar ginsenosides are formed through the manufacture of red ginseng from white ginseng, researchers have generally thought that nonpolar ginsenosides do not exist in white ginseng. Methods: We developed a simultaneous quantitative method for six nonpolar ginsenosides in white ginseng using reverse-phase high-performance liquid chromatography coupled with integrated pulsed amperometric detection. The nonpolar ginsenosides of white ginseng were extracted for 4 h under reflux with 50% methanol. Results: Using the gradient elution system, all target components were completely separated within 50 min. Nonpolar ginsenosides were determined in the rhizome head (RH), main root (MR), lateral root, and hairy root (HR) of 6-year-old white ginseng samples obtained from several regions (Geumsan, Punggi, and Kanghwa). The total content in the HR of white ginseng was 37.8-56.8% of that in the HR of red ginseng. The total content in the MR of white ginseng was 5.9-24.3% of that in the MR of red ginseng. In addition, the total content in the RH of white ginseng was 28.5-35.8% of that in the HR of red ginseng Conclusion: It was confirmed that nonpolar ginsenosides known to be specific components of red ginseng were present at substantial concentrations in the HR or RH of white ginseng.

• Journal of the Korean Electrochemical Society
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• v.7 no.4
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• pp.206-210
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• 2004

All array of carbon paste-based electrodes was prepared by screen printing the carbon paste modified with metal oxides $(TiO_2,\;RuO_2,\;PbO_2,\;Ni(OH)_2)$ and Prussian blue (PB). An electronic tongue system was assembled with the carbon-paste electrode array, and applied to discriminate the tastes of various commercial beverages and foods by measuring the chronoamperometric responses to the samples diluted in 0.1M carbonate buffer (pH 9.6). The results were analyzed with principal component analysis(PCA) method and plotted on two dimensional PCA coordinate; it was apparent that the amperometric electronic tongue system could discriminate the types of various foods and beverages.

• Journal of Sensor Science and Technology
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• v.7 no.4
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• pp.271-278
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• 1998

A ISFET-based glucose sensor has inherent problems such as low sensitivity, drift effect and long response time. For that reason, a amperometric actuation technique was introduce to make a highly sensitivity of the ISFET glucose sensor with a Pt actuator, which electrolyzes $H_2O_2$, one of the by a by-products of the oxidation reaction of glucose. Moreover, a potential-step measurement method detecting response by only the electrolysis of $H_2O_2$ was developed for eliminating a drift problem. The operation characteristics of ISFET-based glucose sensor was improved by using the amperometric actuation and a measurement techniques. The fabricated ISFET glucose sensor is shown good operation such as characteristics(30mM PBS, about 26mV/decade) and linearity. A portable glucose meter with a highly resolution by using the fabricated ISFET-based glucose sensor with Pt actuation was developed and its characteristics investigated.