• Bulletin of the Korean Chemical Society
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• v.25 no.4
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• pp.447-451
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• 2004

Low and high resolution inductively coupled plasma mass spectrometry (ICP-MS) coupled with ion chromatography (IC) has been investigated for speciation of Cr(III) and Cr(VI). In particular, the interference of ArC^+formed by the carbon in a sample on the simultaneous determination of Cr(III) and Cr(VI) has been studied. In chemical speciation, this study shows that quadrupole type ICP-MS with low resolution has a limitation of simultaneous determination fo chromium species if the sample contains the carbon elements. The interference problems can be solved by high resolution ICP-MS.

• Bulletin of the Korean Chemical Society
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• v.23 no.1
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• pp.29-34
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• 2002

The microphase adsorption - spectral correction (MPASC) technique was described and applied to study the interaction of fluorescein isothiocyanate (FITC) with cetyl trimethylammonium bromide (CTAB). The synergism mechanism of micelle was analyzed and discussed. The aggregation of FITC on CTAB obeys the Langmuir monolayer adsorption. Results showed that the monomer and micellar aggregate is $FITC-CTAB_3$ and $(FITC-CTAB_3)_{29}$, respectively at pH 9.62. The adsorption constant of the CTAB-FITC aggregate was determined to be $2.10{\times}10^5$. Interestingly, it was observed for the addition of an anionic surfactant to desorb FITC from its CTAB aggregate and this has been applied to the quantitative determination of trace amounts of anionic detergent (AD) in sewage.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1535-1542
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• 2010

Spectrophotometric micro determination of allopurinol (ALP) via charge-transfer formation is described. This includes the utility of some $\pi$-acceptors such as 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 3,6-dichloro-2,5-dihydroxy-p-benzoquinone (p-CLA) for estimation of ALP drug (act as $\grave{e}$-donor). These reactions are applied for determination of ALP in its pharmaceutical preparations coming from different companies. Elucidation of the chemical structure of the solid CT complexes formed via reaction between drugs under study and $\pi$-acceptors, using elemental analyses (C, H, N), I. R., $^1H$ NMR and mass spectrometry.

• Journal of the Korean Chemical Society
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• v.29 no.4
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• pp.382-389
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• 1985

The effect of plasma operational parameters for the determination of rare earth elements(REE) by means of inductively coupled plasma(ICP) spectrometry was investigated. While the increase in the flow rate of carrier gas argon enhanced the sensitivity and lowered the detection limit, significant ionization interferences were observed. The decrease in RF power increased the signal to background ratio. The observation point showing the lowest ionization interference was slightly higher than the position where the spatial profile of the analyte reached the maximum. The detection limits of the spectral lines commonly used for the determination of REE were measured and the spectral lines relatively free from spectral interferences were chosen.

• Bulletin of the Korean Chemical Society
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• v.25 no.4
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• pp.517-524
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• 2004

Two simple and sensitive spectrophotometric methods were developed for the determination of carbocisteine, penicillamine, ethionamide and thioctic acid in bulk and in their pharmaceutical preparations using alkaline potassium permanganate as an oxidizing agent. The first one involves determination of ethionamide and thioctic acid by spectrophotometric investigation of the oxidation reaction of the two drugs. The second method involves determination of carbocisteine and penicillamine by kinetic studies of the oxidation reaction of these two drugs at room temperature for a fixed time of 20 minutes. The absorbance of the colored manganate ions was measured at 610 nm in both methods. 1-10 ${\mu}$g/mL of ethionamide and thioctic acid could be etermined by the spectrophotometric method with detection limits of 0.11 and 0.089 ${\mu}$g/mL for the two drugs respectively. 2-10 ${\mu}$g/mL of carbocisteine and penicillamine could be determined by the kinetic method with detection limits of 0.14 and 0.21 ${\mu}$g/mL respectively. The two methods were successfully applied for the determination of these drugs in their dosage forms.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1182-1186
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• 2010

A novel poly(safranine)-modified electrode has been constructed for the determination of 4-nitrophenol (4-NP) in natural water sample. The electrochemical behavior of poly(safranine) film electrode and its electrocatalytic activity toward 4-NP were studied in detail by cyclic voltammetry (CV) and adsorptive linear stripping voltammetry (LSV). All experimental parameters were optimized and LSV was proposed for its determination. In optimal working conditions, the reduction current of 4-NP at this poly(safranine)-modified electrode exhibited a good linear relationship with 4-NP concentration in the range of $8.0{\times}10^{-8}$ to $4.0{\times}10^{-5}mol\;L^{-1}$. The detection limit was $3.0{\times}10^{-8}mol\;L^{-1}$. The high sensitivity and selectivity of the sensor were demonstrated by its practical application for the determination of trace amounts of 4-NP in natural water and fruit samples.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1604-1608
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• 2006

A simple and efficient cloud point extraction-spectrofluorimetric method for the determination of thiamine in human urine is proposed. The procedure is based on the oxidation of thiamine with ferricyanide to form thiochrome, its extraction to Triton X-114 micelles and spectrofluorimetric determination. The variables affecting oxidation of thiamine, extraction and phase separation were studied and optimized. Under the experimental conditions used, the calibration graphs were linear over the range 2.5-1000 ng $mL^{-1}$. The limit of detection was 0.78 ng $mL^{-1}$ of thiamine and the relative standard deviation for 5 replicate determinations of thiamine at 400 ng $mL^{-1}$ concentration level was 2.42%. Average recoveries between 93-107% were obtained for spiked samples. The proposed method was applied to the determination of thiamine in human urine.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.213-215
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• 2004

An indirect, sensitive and accurate method for the determination of trace amounts of hydrazine is described. The method is based on the oxidation of hydrazine by a known excess of iodate in the presence of hydrochloric acid. The unreacted iodate is used in the oxidation of hydroxylamine to nitrite. Sulfanilic acid is diazotized by the nitrite formed. The resulting diazonium ion is coupled with N-(1-naphthyl)ethylenediamine to form a stable azo dye, which shows an absorption maximum at 540 nm. Hydrazine can be determined in the range of 20-400 ng $mL^{-1}$ with a detection limit of 3.1 ng $mL^{-1}$. The relative standard deviation for 50, 200 and 400 ng $mL^{-1}$ of hydrazine is 2, 1.5 and 1.3%, respectively (n = 10). The method was applied to the determination of hydrazine in water samples.

• Bulletin of the Korean Chemical Society
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• v.25 no.7
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• pp.1009-1011
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• 2004

In the present work a very simple, sensitive and selective spectrophotometric method for the determination of nitrite in micellar media is described. The method is based on the color reaction of nitrite with p-nitroaniline in the presence of diphenylamine in acid media. In order to remove the extraction step, Triton X-100, a non-ionic surfactant was used as micellar media. The optimum reaction conditions such as acid concentration, reagents concentration and effect of time have been studied and the analytical characteristics of the method such as limit of detection, linear range and molar absorptivity have been obtained. The interference of some anions and cations was also tested. The method was applied to the determination of nitrite in real samples.

• Journal of the Korean Chemical Society
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• v.4 no.1
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• pp.10-12
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• 1957

On the performance of the hydrogen peroxide method for Th-determination we encountered some difficulties, namely the formation of the insoluble matter occured in the nearly neutral solution after evaporation. We carried out the Th-determination in the mixture of the Th and some kind of the rare earth, and found that the insoluble matter was not formed in case of the mixture of Th and some kind of rare earth, but formed in case of Monazite. The formation of the insoluble matter in the case of Monazite sand, however, could be avoid by using the beaker instead of the evaporating dish and by adding the water repeatedly before it was completely evaporated to dryness.