• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.638-643
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• 1992

The analytical response properties of two types of continuous flow-through electrode system as fulfide ion detectors are examined and directly compared their reponse characteristics under the optimal conditions. In both detection systems, observed peak potentials are logarithmically related to the sulfide ion concentration and at least twenty samples per hour can be determined. In the pH electrode method, the pH of the flowing recipient stream leaving the dialyzer was monitored. The designed system involves the use of continuous flow gas dialyzer in conjunction with the tubular polymer membrane electrode. In this method, optimal experimental conditions are recipient of mixture of $5.0 {\times} 10^{-5} M NaOH ＋ 5.0 {\times} 10^{-3} M$ NaCl and diluent of 0.10 M $H_2SO_4$, and all flow rates of recipient stream, diluent stream, and sample are 1.0 ml/min. In the sulfide ion electrode method, a commercially available sulfide ion-selective electrode was used to detect sulfide ion in the flow-through cell. The optimal flow rates of sulfide anti-oxidant buffer (3.5 g ascorbic acid and 7.6 g $Na_2EDTA$ dissolved in 1.0 M NaOH solution 1 l) and sample were 1.4 ml/min and 1.0 ml/min, respectively.

• Journal of the Korean Chemical Society
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• v.44 no.6
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• pp.541-546
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• 2000

Methods to determine L-dopa(L-3,4-dihydroxyphenylalanine) in aqueous solution by spectrofluorimetry based upon the ligand sensitized luminescence of Tb(III) ion L-dopa complex have been studied. Tb(III) ion and Lu(III) ion were used as ligand sensitized fluorescencer and co-fluorescence enhancer, respectively. The effects of excitation wavelength, pH, concentration of Tb(III) ion, concentration of Lu(III) ion and emission wavelength on the fluorescence intensity were investigated. The fluorescence intensity of the Tb(III) ion L-dopa complex was further increased with addition of Lu(III) ion. The calibration curve for L-dopa was linear over the range from 5.0 ${\times}$ $10^{-7}$ M to 1.0${\times}$ $10^{-4}$ M and the detection limit was 4.0 ${\times}$ $10^{-8}$ M under the optimal experimental conditions of 300 nm, 8.0, 1.0 ${\times}$ $10^{-4}$ M and 545 nm for excitation wavelength, pH, concentration of Tb(III) ion and emission wavelength, respectively. When Lu(III) ion was added to Tb(Ⅲ) ion L-dopa complex, the concentration range of linear response and detection limit were 1.0${\times}$$10^{-8}$ M to 2.0 ${\times}$ $10^{-4}$ M and 1.0 ${\times}$ $10^{-9}$ M, respectively under the optimal experimental conditions of 300 nm, 8.5, 1.0 ${\times}$ $10^{-5}$ M, 1.0 ${\times}$ $10^{-5}$ M, 545 nm for excitation wavelength, pH, concentration of Tb(III) ion, concentration of Lu(III) ion and emission wavelength, respectively.

• Journal of the Korean Chemical Society
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• v.39 no.9
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• pp.705-714
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• 1995

A new analytical luminescence method for the Eu+3 and Tb+3 ions was studied using the luminescence enhancement by the treatment of the o-phenanthroline on the nylon membrane. Compared to the specific emission intensities of the ions in aqueous(or ethanol) solution, if the aqueous ion is spotted on the nylon membrane, the luminescence intensities were extremely enhanced. There was additional enhancement effect of the luminescence intensities of the ions on the nylon membrane, if the ion on the nylon membrane is treated with o-phenanthroline. Based on the luminescence enhancement, the detection limits were lowered by more than 7 order of magnitude compared to that of solution sample, and also lowered by about 1 order of magnitude compared to that of previous TLC method. The dynamic ranges and correlation coefficients of the calibration curves near the detection limit were 2∼3 order and ∼0.99, respectively. It was also shown that the luminescence intensity was in its maximum when the ion on the nylon is treated with ∼4 mole ratio of o-phenanthroline. The energy-transfer mechanism was explained for the theoretical background of the luminescence enhancement.

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.473-479
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• 2016

We report a highly selective and sensitive 200 MHz Surface Acoustic Wave (SAW) sensor that can detect cyanide ion in aqueous solution using surface immobilized thioester molecules in combination with gold nanoparticles (AuNPs). To construct the sensor device, a monolayer of thioester compound was immobilized on the SAW sensor surface. At the sensor surface, hydrolysis of thioester group by nucleophilic addition of cyanide occurred and the resulting free thiol unit bound to AuNP to form thiol-AuNP conjugate. For the signal enhancement, gold staining signal amplification process was introduced subsequently with gold (III) chloride trihydrate and reducing agent, hydroxylamine hydrochloride. The SAW sensor showed a detection ability of $17.7{\mu}M$ for cyanide in aqueous solution and demonstrated a saturation behavior between the frequency shift and the concentration of cyanide ion. On the other hand, our SAW sensor had no activities for other anions such as fluoride ion, acetate ion and sulfate ion, moreover, no significant interference observed by other anions. Finally, all the experiments were carried out in-house developed sensor and fluidics modules to obtain highly reproducible results.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.421-427
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• 1996

Ethyl carbamate is an animal carcinogen and a suspected human carcinogen found in fermented foods and beverages. For the determination of ethyl carbamate in typical Korean diet, an analytical method was established for the food as complex as Kimchi. Kimchi samples collected from various locations in the country were homogenized and extracted four times with ethyl acelate. Following concentration and reconstitution with water, the extract was loaded onto $C_{18}$ column. Fraction containing ethyl carbamate was eluted with methanol, while most of the red pigment of the sample was retained on the column. The eluent was further purified with alumina, followed by Florisil column. The final eluent was analyzed by gas chromatography mass spectrometry in the selected ion monitoring mode. None of the twenty Kimchi samples showed ethyl carbamate level higher than 4.6 ppb without correction for the recovery. The concentration of ethyl carbamate in Kimchi increased as pH decreased, suggesting fermentation dependent formation of ethyl carbamate.

• Korean Journal of Crystallography
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• v.17 no.2
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• pp.60-65
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• 2006

표면 및 계면층의 결정구조, 결함구조, 불순물 편석, 표면의 전자 구조, 원자 진동 등과 같은 산화물의 표면물성은 촉매, 센서, 소결, 마찰, 부식 등과 같은 분야에서 그 특성을 좌우한다. 고체 표면의 결정구조 해석 수단으로 저에너지 이온산란 분광법이 유용한 도구로 알려져 있는데, 이 방법의 뛰어난 표면민감성은 표면에서의 효과적인 이온 중성화 과정에 기인한다. $He^+$, $Ne^+$, $Ar^+$ 등과 같은 이온은 Auger 중성화 과정에 의하여 쉽게 중성원자화 되고, 중성화 확율의 타겟에 대한 의존성이 낮기 때문에 이온빔으로서 종종 사용된다. 산란각도를 180$^{\circ}$로 고정하여 산란이온 검출기를 설치한 직충돌 이온산란 분광법의 경우는 산란된 이온의 궤적이 입사궤도와 거의 동일하기 때문에 산란궤적의 계산이 간단해지고, 수 층 깊이의 원자구조의 해석이 가능해진다. 본 고에서는 고체 표면의 원자구조를 실공간에서 해석할 수 있는 직충돌 이온산란 분광법에 대하여 측정의 기본원리, 측정장치, 간단한 분석 예 등에 관하여 기술하고자 하며, 다음 편에서는 복잡한 표면구조를 가지는 반도체 표면에서 직충돌 이온산란분광법의 이용하여 해석한 예를 중심으로 기술하고자 한다.

• Journal of environmental and Sanitary engineering
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• v.13 no.1
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• pp.195-202
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• 1998

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.7 s.250
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• pp.638-645
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• 2006

Recently, we reported that significant ion loss occurred prior to its detection in the conventional single particles mass spectrometry and more seriously the loss is ion-kinetic-energy-dependent. These lead to significant error in the measured chemical composition of nanoparticles. Here we attempted to design a novel ion optics that is capable of 100% detection of ions generated from single nanoparticle. Using a commercial software SIMION, we simulated the trajectories of ions launched at different speeds inside the previous single particle mass spectrometer We tested how affect changes in shape of repelling plate, adding Einzel lens, substitution of tube electrode between extraction and acceleration grids. As a results, we could find a best design by assembling the trials in the present condition.

• Journal of the Korean Chemical Society
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• v.45 no.1
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• pp.25-30
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• 2001

A selective kinetic fluorimetric method for the determination of trace rhodium(Ⅲ), based on the catalytic effect of rhodium(Ⅲ) on the oxidation of nile blue by periodate have been studied. The effects of pH and concentrations of nile blue, sodium periodate, trioctyl phosphine oxide(TOPO) and temperature were investigated. The calibration curve for rhodium(Ⅲ) ion was linear over the range from 100 ng/mL to 0.1 ng/mL and the detection limit was 0.01 ng/mL under the optimal experimental conditions. Effects of interferences from several cations and anions for the determination of rhodium(Ⅲ) were also investigated.

• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.505-509
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• 2012

In this study, we investigate the use of new carbon nanotube paste electrode (CNPE) for promoting the detection of lead (Pb) heavy metal in the a drinkable water, which negatively affects human brain and nerve system. For the evaluations, CNPE is served as a working electrode, while sensitivity and limit of detection (LOD) of Pb are measured in DI and tap water based electrolytes using squarewave anodic stripping voltammetry (SWASV). As a result of that, in the 25~150 ppb range of $Pb^{2+}$ ions, its sensitivity and calculated LOD are $12.85\;{\mu}A/{\mu}M$ and 26 ppb in DI water based 0.1 M $H_{2}SO_{4}$ electrolyte while they are $10.36\;{\mu}A/{\mu}M$ and 38 ppb electrolytes respectively. In addition, experimentally measured LOD values of Pb are 4 ppb and 10 ppb in the two water electrolytes. The stripping of $Pb^{2+}$ ion is also controlled by surface reaction. Our experimental data are then compared with those of other already published references. With the comparison, it is proved that our electrode outperforms other electrodes in terms of the sensitivity and LOD of trace Pb metal.