• 대한화학회지
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• 제33권2호
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• pp.208-214
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• 1989

구리(Ⅱ)와 코발트(Ⅱ)의 테트라 티오시안 착이온은 Amberlite LA 1, Alamine 336 또는 Aliquat 336과 같은 고분자량 알킬아민과 이온쌍 화합물이 형성되면 붉은색과 푸른색을 띠어 파장 480nm와 625nm에서 각각 최대 흡수 봉우리를 나타내므로 같은 조건에서 이들 이온쌍 화합물을 methyl isobutyl ketone으로 동시 추출하여 분광광도법으로 두 금속원소를 동시 정량하는 방법을 기술하였다. 그러나 각 흡수스펙트럼이 서로 조금씩 겹치기 때문에 흡광도로부터 농도를 구하기 위하여는 두개의 연립방정식이 필요했다. Fe(Ⅲ)와 Ni(Ⅱ)은 적은 양이 공존하더라도 구리 정량에 영향을 주었다. 이 동시정량법에 의해서 강철과 광물시료의 분석결과는 구리와 코발트 원소를 각각 분석한 결과와 잘 일치하였다.

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1516-1520
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• 2009

A sensitive technique for the determination of trace Co(II) in various samples after column preconcentration by adsorbing onto silica gel loaded with 1-nitroso-2-naphthol was developed. Several experimental conditions, such as pH of sample solution, the amount of silica gel loaded with 1-nitroso-2-naphthol, the flow rate for adsorption and so forth, were optimized. The interfering effects of diverse concomitant ions were investigated. Fe(III) interfered with more than any other ions, but the interference by Fe(III) was completely eliminated by adjusting the amount of silica gel loaded with 1-nitroso-2-naphthol to 0.30 g. The dynamic range, the correlation coefficient ($R^2$), and the detection limit obtained by the proposed technique were 3.0-140.0 ng m$L^{-1}$, 0.9942, and 1.81 ng m$L^{-1}$, respectively. For validating the technique, the aqueous samples (tap water, reservoir water, stream water, and wastewater) and the plastic samples were used as real samples. Recovery yields of 93.0-107.0% were obtained. These measured data were not different from ICP-MS data at the 95% confidence level by F test. Based on the results of the experiment, it has been found that the proposed technique can be applied to the determination of Co(II) in various real samples.

• Journal of Biosystems Engineering
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• 제36권5호
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• pp.326-333
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• 2011

The need for rapid on-site monitoring of hydroponic macronutrients has led to the use of ion-selective electrodes, because of their advantages over spectrophotometric methods, including simple methodology, direct measurement of analyte, sensitivity over a wide concentration range, and low cost. Stability and repeatability of response can be a concern when using multiple ion-selective electrodes to measure concentrations in a series of samples because accuracy might be limited by drifts in electrode potential. A computer-based measurement system could improve accuracy and precision because of both consistent control of sample preparation and easy calibration of sensors. Our goal was to investigate the applicability of a cobalt-based electrode used in conjunction with a laboratory-made automated test stand for quantitative determination of ${PO_4}^-$ in hydroponic solution. Six hydroponic solutions were prepared by diluting highly concentrated paprika hydroponicsolution to provide a concentration range of 1 to 300 ppm $PO_4$-P. A calibration curve relating electrode response to phosphate in paprika hydroponic solution titrated to pH 4 with 0.025M KHP was developed based on the Nikolskii-Eisenman equation with a coefficient of determination ($R^2$) of 0.94. The laboratory-made test stand consisting of three cobalt-based electrodes measured phosphate concentrations similar to those obtained with standard laboratory methods (a regression slope of 0.98 with $R^2$ = 0.80). However, the y intercept was relatively high, 30 ppm, probably due to the relatively large amount of variation present among multiple measurements of the same sample. Further studies on the high variation in EMFs obtained with cobalt electrodes during replicate measurements were required for P estimations comparable to those obtained with standard laboratory instruments.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2001년도 추계학술대회 및 정기총회
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• pp.114-114
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• 2001

Since hypoxia-inducible factor-lalpha (HIF-lalpha) and the arylhydrocarbon receptor (AhR) shared the AhR nuclear translocator (Arnt) for hypoxia- and AhR-mediated signaling, respectively, it was possible to establish the hypothesis that hypoxia could regulate Cyplal expression. In order to understand the mechanism of Cyplal gene expression, we demonstrated here that hypoxic agents such as cobalt chloride, desferrioxarnine, and picolinic acid reduced the TCDD induced Cyplal promoter activity based on the determination of luciferase activity in Hepa I cells transfected with pmCypla1-Luc. Also cobalt chloride inhibited the TCDD stimulated Cyplal mRNA level as well as EROD activities in both Hepa I and MCF-7 cells. Hypoxic agents such as cobalt chloride, picolinic acid, and desferrioxamine showed inhibition of luciferase activity that was induced by lnM TCDD treatment with dose dependent manner. Concomitant treatment of 150${\mu}$M ferrous sulfate with 1∼100${\mu}$M desferrioxarnine or 1∼100${\mu}$M picolinic acid recovered from the hypoxic agents-inhibited luciferase activity that was stimulated by TCDD. Reciprocally, the hypoxic agents down regulated TCDD induced Cyplal mRNA level and CYP1A1 enzyme activity in Hepa I cells.

• Bulletin of the Korean Chemical Society
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• 제25권5호
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• pp.694-698
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• 2004

A new method for the simultaneous determination of seven transition metal ions in water and food by microcolumn high-performance liquid chromatography has been developed. The lead, cadmium, mercury, nickel, cobalt, silver and tin ions were pre-column derivatized with tetra-(4-aminophenyl)-porphyrin ($T_4$-APP) to form the colored chelates which were then enriched by solid phase extraction with $C_{18}$ cartridge. The enrichment factor of 50 was achieved by eluted the retained chelates from the cartridge with tetrahydrofuran (THF). The chelates were separated on a ZORBAX Stable Bound microcolumn ($2.0{\times}50\;mm,\;1.8\;{\mu}m$)with methanol-tetrahydrofuran (95 : 5, v/v, containing 0.05 mol/L pyrrolidine-acetic acid buffer salt, pH = 10.0) as mobile phase at a flow rate of 0.5 mL/min and detected with a photodiode array detector from 350-600 nm. The seven chelates were separated completely within 2.0 min. The detection limits of lead, cadmium, mercury, nickel, cobalt, silver and tin are 4 ng/L, 3 ng/L, 6 ng/L, 5 ng/L, 5 ng/L, 6 ng/L, 4 ng/L respectively in the original samples. This method was applied to the determination of the seven transition metal in water and food samples with good results.

• 약학회지
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• 제28권2호
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• pp.61-67
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• 1984

A method is described for the spectrophotometric determination of platinum (IV) with 2-oximino-1-indanone based on solvent extraction of Pt:2-oximino-1-indanone complex. The 2-oximino-1-indanone reacted with Pt(IV) to form a dark-orange complex which shows a characterisic maximum absorption at 342nm. The optimum PH for the platinum extraction lies between 5.4~8.0. Beer's law obeys up to 0.98-16.3ppm of platinum (IV) and the molar absorption coefficient is $1.06{\times}10^{-4}L.mol^{-1}.cm^{-1}$. The relative standard deviation of the method was $\times2.1%$. The composition of the complex is estimated to be Pt : In= 1 : 1, by the mole ratio method and ion exchange resin experiment. The optimum condition for the determination of platinum has been studied in detail. The 2-oximin-1-indanone is found to be a selectivereagent for the determination of platinum, since the synthesixed 2-oximino-1-indanone did not react with other metals such as cobalt, cadmium, copper, manganese nickel, iron, lead and zinc, to form the complex. In this studies, we have also clarified Sindhwani and Singh's spectrophotometric determination data of various metals with acenaphthenequinone monooxime (Talanta 20,248, 1973), whose results were not correct.

• 한국환경농학회지
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• 제29권1호
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• pp.72-76
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• 2010

본 연구에서는 탄소 유기물과 CoPh를 혼합하여 농약 잔류량을 측정 할 수 있는 바이오센서를 구현 하였다. 작동 전극은 탄소유기물과 CoPh를 섞어 사용하였고 비율은 CoPh를 7%로 제작하였다. CoPh가 7%인 경우 저농도 thiocholine 농도에서도 민감하게 반응하였다. 대표적인 농약인 카보후란에 대하여 센서의 감도 한계는 약$0.5{\mu}g/L$ 수준이며, 농약 농도에 따른 전극의 출력이 선형적인 결과를 얻었다. 또한 EPN 및 클로로피리포스 농약에 대하여 실험 한 결과 카보후란과 같이 농도에 따라 효과적으로 반응하는 것을 확인하였다. 이러한 센서는 현재 농약 잔류량 측정에 사용되는 비색법과 비교하여도 감도 및 선형성 면에서 뒤떨어지지 않으며, 간이 농약 잔류량 측정기 센서로 사용가능성이 있다.

• 대한화학회지
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• 제43권6호
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• pp.644-650
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• 1999

본연구에서 유기 침전제를 사용하여 수용액중의 코발트를 on-line으로 연속 침전시켜 선농축하는 방법을 연구하였다. 침전제로 1-nitroso-2-naphthol을 사용하여 라인내에서 직접 침전시킨 뒤 MlBK(Methyl lsobutyl Ketone)로 용해시켜 불꽃 원자흡수 분광기로 보내어 분석하였다. 최적조건을 구하고 농축배율을 연구한 결과 대개 0.5 ppm의 코발트 시료 1.0 mL를 사용하였을 때 13배의 농축율을 얻었으며 시료 처리 속도는 시간당 I0개 정도 이었다. 부피를 10.0 mL로 증가시키면 시료의 처리속도는 늦어지지만 농축비를 68배로 높일 수 있었다. 본 연구의 정확성을 알기 위해 합성된 준 표준 생체시료를 분석한 결과 4%의 상대 표준편차를 가지고 예상치에 근접하는 좋은 결과를 얻을 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제25권8호
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• pp.1137-1142
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• 2004

A spectrophotometric and first derivative spectrophotometric method was developed in aquatic Tween 80 micellar solutions for selective determination of nickel without using any pre-separation step. 1-(2-Pyridylazo)-2-naphthol (PAN), as a sensitive chromogenic complexing agent formed a red-colored Ni(II)-PAN complex in Tween 80 media with satisfactory solubility and stability. Conditions such as pH, PAN concentration, type and concentration of micellizing agent were optimized. Molar absorptivity of Ni-PAN complex was found $4.62\;{\times}\;10^4L\;cm^{?1}\;mol^{?1}$ at 569 nm, under the optimum condition. Calibration graphs were derived by zero, first and second derivative spectrophotometry at maximum wavelengths of 569, 578 and 571 nm with linear ranges of 30-1800, 20-2500 and 30-2000 ng $mL^{?1}$ , respectively. Precision as standard deviation as well as accuracy as recovery percent were in the range of 1-20 ng $mL^{?1}$, and 93.3-103.3%, respectively, for the entire of the linear ranges. Spectrophotometric detection limit was 3 ng $mL^{?1}$ and effects of diverse ions on the first derivative determination of nickel were studied to investigate selectivity of the method. Interferences of cobalt and copper on the nickel determination were prevented using o-phenanthroline as masking agent. The recommended procedures were applied to the various synthetic and stainless steel alloys, tea leaves and human hair, with satisfactory results.

• 한국세라믹학회지
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• 제14권2호
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• pp.73-77
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• 1977

The surface diffusion coefficients for nickel, nickel oxide, cuppric oxide, cobalt oxide, alumina and ferric oxide have been determined at various temperatures using the sintering technique. This investigation is based on the model accounting for the sum of the contribution of volume and surface diffusion to the overall shrinkage rate during the initial stage of sintering. Simultaneous measurements of shrinkages and shrinkage rates of the materials compacts were conducted for various annealing times, the results of which were then correlated to the diffusion coefficient.