• Journal of the Korean Chemical Society
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• v.41 no.6
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• pp.320-323
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• 1997

• Journal of the Korean Chemical Society
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• v.52 no.6
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• pp.622-629
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• 2008

• Journal of the Korean Chemical Society
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• v.41 no.4
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• pp.219-221
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• 1997

• Journal of the Korean Chemical Society
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• v.33 no.3
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• pp.304-308
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• 1989

The spectrophotometric determination of $Lu^{3+},\;Eu^{3+}$ and some other rare earths have been investigated using Methyl Thymol Blue(MTB) as spectrophotometric reagent. Rare earth elements form a stable complex with MTB abount pH 6.5 and the ratio of its complex is 1 to 1. MTB has a absorption maxima at 440nm and rare earth MTB complex has absorption maxima 610nm at pH 6.5, respectively. The absorbance of the rare earth MTB complex is stable in 7 hours after color developing and obey the Beer law in the range of $0{\sim}110{\mu}g/50ml$. The ligand such as phosphate, citrate and EDTA decrease the absorbance of its complex considerably, and this method has a poor selectivity of each rare earth element and the molar absorptivity is $1.2{\sim}2.0{\times}10^4mol^{-1}{\cdot}l{\cdot}cm^{-1}$. In methyl alcohol, ethyl alcohol and acetone medium we did not find out any absorption change of the rare earth MTB complex.

• YAKHAK HOEJI
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• v.31 no.5
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• pp.330-337
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• 1987

The weak UV absorbing ephedrine alkaloids such as ephedrine, pseudoephedrine, methylephedrine and norephedrine could be analyzed by charge-transfer spectrophotometric method. The results obtained are summarized as follows: (1) It was possible to determine a weak UV absorbing ephedrine alkaloids using the intense charge-transfer UV bands in chloroform. (2) This method was suitable for the spectrophotometric determination of ephedrine alkaloids in mixed pharmaceutical preparation. (3) Linear relationship was found between absorbance and concentration in the range of 1.0$\times$$10^{-5}M$~5$\times$$10^{-5}M$ of ephedrine ($\varepsilon$= 2.72$\times$$10^{4}LM^{-1}cm^{-1}$ and pseudoephedrine ($\varepsilon$=2.84$\times$$10^{4]LM^{-1}cm^{-1}$), 1.0$\times$$10^{-5}M$~5$\times$$10^{-5}$M of methylephdrine ($\varepsilon$=1.68$\times$$10^{4}LM^{-1}cm^{-1}$) and 1/3$\times$$10^{-4}M$~4/3$\times$$10^{-4}M$ of norephedrine ($\varepsilon$=0.74$\times$$10^{4}LM^{-1}cm^{-1}$. (4) CT- complex of ephedrine, pseudoephedrine and methylephedrine has absorption maxima at 293nm and norephedrine have absorption maximum at 253nm. (5) CT-complexes were formed in a 1:1 ratio between ephedrine alkaloids and iodine in chloroform. (6) By UV, IR, and $^1H$-NMR spectra, it could be inferred that CT-complexes were formed by interaction between the basic nitrogen of ephedrine alkaloids as electron (n) donor and iodine as electron ($\sigma$) acceptor.

• Journal of the Korean Chemical Society
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• v.19 no.5
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• pp.343-350
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• 1975

About 20${\sim}$100${\mu}g$ iridium have been extracted quantitatively as stannous-chloro Complex from aqueous solution by Alamine-336, a high molecular weight tertiary amine, dissolved in benzene. The extractability was confirmed by radioactive tracer of iridium-192. The spectrophotometric measurements of the extracted species at 322.5 nm indicate the feasibility of this method to be used as an analytical procedure for the determination of micro amount of iridium. An anion model of stannous-chloro complex of iridium has been postulated to account for the extraction mechanism.

• Journal of Life Science
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• v.21 no.4
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• pp.610-612
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• 2011

We developed a spectrophotometric assay for the quantitative determination of chlorogenic acid based on the formation of green pigment at $50^{\circ}C$ under glycine and alkaline conditions in 96-well plates. The formation of green pigment was linear with a series of chlorogenic acid concentration (0-$300\;{\mu}M$). Using this method, the content of chlorogenic acid (12.42 mg/g dry weight) in the leaves of blueberry was quantified. This method is high-throughput, cost-effective, rapid, and easy to perform.

• Journal of the Korean Chemical Society
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• v.9 no.2
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• pp.101-105
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• 1965

Spectrophotometric method for the determination of Co(Ⅱ) is developed based on the fact that Co(Ⅱ) forms a stable red complex with 7-nitroso-8-hydroxyquinoline-5-sulfonate at pH 4. 5. The absorbance is measured at 528$m{\mu}$, $25^{\circ}C$. Beer's law is followed in the concentration range of 0. 3 to 6. 0 p.p.m. of Co(Ⅱ) and molar extinction coefficient of the complex was $1.1{\times}10^4$. Of the diverse ions checked, Fe(Ⅱ), Fe(Ⅲ), Cu(Ⅱ), Mn(Ⅱ), Hg(Ⅰ), CN-, EDTA interfere. The composition of the complex is found to be 3:1 ligand to metal species by mole ratio and continuous variation methods.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.616-621
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• 1990

The spectrophotometric methods for the determination of Nd, Pr, Sm, Eu, Ho, Er were developed, using the multicomponent method of absorption spectra cointerference. The absorption spectra of individual Nd, Pr, Sm, Eu, Ho, Er, mixture of Sm, Eu, Ho, Er in hydrochloric acid solutions were investigated, and also a band register which includes the molar absorptions for all trivalent Nd, Pr, Sm, Eu, Ho and Er absorption band maxima were measured. The spectrophotometric determination of Nd, Pr, Sm, Eu, Ho and Er were investigated using the analytically significant absorption bands at 444.2, 575.1, 401.7, 394.2, 416.6, and 379.7 nm, respectively.

• Analytical Science and Technology
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• v.12 no.6
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• pp.515-520
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• 1999

The spectrophotometric determination of Al(III) with thorin have been investigated. The optimum condition of pH, concentration of ligand and surfactant, and stability were evaluated. The thorin ligand offers selective separation of Al(III) from sample solution containing Fe(III), Ni(II), Cu(II), Pb(II) and Cu(II). Various surfactants were tested and Triton X-100 showed the best stability and the maximum absorbance in an aqueous solution of Al(III)-Thorin-Triton X-100 complex appears about 526 nm. The method was applied for the determination of Al(III) in mixed sample solution. Separation and preconcentration was performed with a short column filled with resorcinol-formaldehyde resin. Control of the pH during the column operation is essential because the adsorption capacities are very sensitive to change in pH. Their separation was carried out in 0.2 M acetic acid-sodium acetate buffer solution (pH 4.5) and 1.0 M $HNO_3$media.