• Journal of Electrochemical Science and Technology
• /
• v.3 no.2
• /
• pp.90-94
• /
• 2012

A simple and sensitive electrochemical sensor for simultaneous and quantitative detection of ranitidine (RT) and metronidazole (MT) was developed, based on a poly(thionine)-modified anodized glassy carbon electrode (PTH/GCE). The modified electrode showed the excellent electrocatalytic activity towards the reduction of both RT and MT in 0.1M phosphate buffer solution (PBS, pH 7.0). The peak-to-peak separations (${\Delta}E_p$) for the simultaneous detection of RT and MT between the two reduction waves in CV and DPV were increased significantly from ca. 100 mV at anodized GCE, to ca. 550 mV at the PTH/GCE. The reduction peak currents of RT and MT were linear over the range from 35 to $500{\mu}M$ in the presence of 200 and $150{\mu}M$ of RT and MT, respectively. The sensor showed the sensitivity of 0.58 and $0.78{\mu}A/cm^2/{\mu}M$ with the detection limits (S/N = 3) of 1.5 and $0.96{\mu}M$, respectively for RT and MT.

• Journal of Electrochemical Science and Technology
• /
• v.11 no.1
• /
• pp.68-83
• /
• 2020

A fast and simple method for synthesis of Cu_xO-ZnO/PPy/RGO nanocomposite by electrochemical manner have been reported in this paper. For testing the utility of this nanocomposite we modified a GCE with the nanocomposite to yield a sensor for simultaneous determination of four analytes namely ascorbic acid (AA), dopamine (DA), uric acid (UA), and folic acid (FA). Cyclic voltammetry (CV) and Differential pulse voltammetry (DPV) selected for the study. The modified electrode cause to enhance electron transfer rate so overcome to overlapping their peaks and consequently having the ability to the simultaneous determination of AA, DA, UA, and FA. To synthesis confirmation of the nanocomposite, Field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and electrochemical impedance spectroscopy (EIS) were applied. The linearity ranges were 0.07-485 μM, 0.05-430 μM, 0.02-250 μM and 0.022-180 μM for AA, DA, UA, and FA respectively and the detection limits were 22 nM, 10 nM, 5 nM and 6 nM for AA, DA, UA, and FA respectively Also, the obtained electrode can be used for the determination of the AA, DA, UA, and FA in human blood, and human urine real samples.

• Analytical Science and Technology
• /
• v.8 no.4
• /
• pp.591-596
• /
• 1995

Enzyme multilayers composed of avidin and biotin-labeled enzymes were prepared on the surface of electrode, through a strong affinity between avidin and biotin (binding constant: ca $10^{15} M^{-1}$). The enzyme multilayers were useful for the improvement of the performance characteristies of enzyme sensors. The output current of the enzyme sensors depended linearly on the number of enzyme layers deposited. Thus, lactate oxidase (LOx) and alcohol oxidase (AlOx) were deposited after being modified with biotin for constructing enzyme sensors sensitive to L-lactate and ethanol respectively. It was also possible to deposit two different kinds of enzymes successively in a single multilayer. The glucose oxidase (GOx) and ascorbate oxidase (AsOx) were built into a multilayer structure on a Platinum electrode. The GOx, AsOx multilayer-modified electrode was useful for the elimination of ascorbic acid interference of the glucose sensor.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.11
• /
• pp.3357-3361
• /
• 2013

Alumina microfibers with porous structures were prepared through hydrothermal reaction, and then used to modify the surface of carbon paste electrode (CPE). After modification with alumina microfibers, the electrochemical activity of CPE was found to be greatly improved. On the surface of alumina microfibers-modified CPE, the oxidation peak current of salvianolic acid B, a main bioactive compound in Danshen with anti-oxidative and anti-inflammatory effects, was remarkably increased compared with that on the bare CPE surface. The influences of pH value, amount of alumina microfibers and accumulation time were studied. Based on the strong signal amplification effects of alumina microfibers, a novel electrochemical method was developed for the detection of salvianolic acid B. The linear range was from 5 ${\mu}gL^{-1}$ to 0.3 mg $L^{-1}$, and the detection limit was 2 ${\mu}gL^{-1}$ (2.78 nM) after 1-min accumulation. The new method was successfully used to detect salvianolic acid B in ShuangDan oral liquid samples, and the recovery was over the range from 97.4% to 102.9%.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.7
• /
• pp.1386-1390
• /
• 2008

Artemisinin, the effective ingredient of Chinese herb Artemisia annua L (Qinghao in Chinese), has been proved to be effective to antimalarial. Herein, a reliable, sensitive and convenient electrochemical method was developed for the determination of artemisinin utilizing the excellent properties of multi-wall carbon nanotube (MWNT). The electrochemical behavior of artemisinin was investigated. It is found that the reduction peak current of artemisinin remarkably increases and the peak potential shifts positively by 240 mV at the MWNT film-modified electrode. These phenomena indicate that the MWNT film exhibits efficient catalytic activity to the electrochemical reduction of artemisinin. The effects of pH value, amount of MWNT, scan rate and accumulation time were examined. The limit of detection (S/N = 3) is as low as 10 $\mu$ g $L^{-1}$. Finally, this newly developed method was used to determine the content of artemisinin in Artemisia annua L.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.6
• /
• pp.1883-1886
• /
• 2013

• Proceedings of the Korean Environmental Health Society Conference
• /
• 2003.06a
• /
• pp.204-207
• /
• 2003

Determination of Lead(II) using nafion-DTPA (diethylene triamine pentaacetic acid)-glycerol-modified glassy carbon electrodes is described. Lead(II) is accumulated at the electrode by complexing with the DTPA, reduced, and detected by differential pulse voltammetry. In this study, we demonstrate that at a preconcentration time of 5min the nafion-DTPA-glycerol-modified glassy carbon electrode has a linear calibration curve at range 1.0${\times}$10$\^$-9/M∼1.0${\times}$10$\^$-7/M in pH 4.0 buffer solution. The detection limit(3$\sigma$) is as low as 5.0${\times}$10$\^$-6/M. This method is applied to the determination of lead(II) in certified reference material and the result agrees satisfactorily with the certified value.

• Journal of the Korean Electrochemical Society
• /
• v.10 no.1
• /
• pp.1-6
• /
• 2007

Mercaptopropionic acid(mpa) has been used to make self-assembled monolayer(SAMs) on the surface of graphite electrode incorporating gold nano particles, which are subsequently modified with dopamine(dopa). Such modified electrodes haying types of Gr(Au)/mpa-dopa were employed in the electrocatalytic oxidation of NADH. The responses of such modified electrodes were studied in terms of electron transfer kinetics and reaction procedure in the reaction. The reaction of the surface immobilized dopa with NADH was studied using the rotating disk electrode technique and a value of $5.06{\times}10^5M^{-1}s^{-1}$ was obtained for the second-order rate constant in 0.1 M phosphate buffer(pH=7.0), which was a $EC_{cat}$ and kinetic controlled procedure. But, the modified electrodes were diffusion controlled reaction having $4.64{\times}10^{-4}cm^2s^{-1}$ of the coefficient within $10^{-3}s$ after starting the reaction.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2002.08a
• /
• pp.601-604
• /
• 2002

We propose modified fence electrode structure for manufacturing of ITO-electrode-free PDP. Luminance, luminance efficiency and addressing time for the proposed structure shows performance improvement about 25 percent. Our results can be used for the reduction of manufacturing cost without degradation of PDP performance.

• Journal of Korean Society for Atmospheric Environment
• /
• v.31 no.6
• /
• pp.530-537
• /
• 2015

The wet electrostatic precipitator (wet ESP) is an effective control device which removes submicron particles reentrained in a collection plate and water soluble gas. However, its collection efficiency decreases, as its operation is subject to water-induced distortion of the collection electrode. In order to make up for the limitation, we modified the wet ESP system by installing electrosprayed discharge electrodes. The modified wet ESP system can wash both the collection plate and discharge electrode. As a result, we were able to fabricate a compact wet ESP with a small specific collecting area ($0.18m^2(m^3/min)$) that can accomplish a high collection efficiency of fine particles (97.1%). In addition, the device obtained a relatively low specific corona power of approximately $10W/(m^3/min)$.