• Analytical Science and Technology
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• v.10 no.5
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• pp.343-349
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• 1997

Analytical method using the reversed phase ion-pair chromatography (RP-IPC) for the determination of kasugamycin(5-amino-2-methyl-6-(2,3,4,5,6-pentahydroxy cyclohexyloxy)tetrahydropyran-3-yl-amino-${\alpha}$-imino acetic acid), pesticide as fungicide bactercide has been established. The retention behavior of kasugamycin in the RP-IPC was examined with respect to the effect of concentrations of organic modifiers, pH of eluent and types and concentrations of the counter ions as ion-pair reagent. This method developed by the optimum factors, can be used for the application of the quality control in the crude product and its formulation.

• KSBB Journal
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• v.18 no.5
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• pp.408-411
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• 2003

By reversed-phase high-performance liquid chromatography, the extraction and separation of glabridin by from licoricce root was performed in this work. The column efficiencies and resolutions of glabridin were investigated with mobile phase composition on the reversed-phase chromatographic system. The glabridin collected from licorice root was identified by LC/MS. The mobile phase used to extract glabridin were composed of ethanol, methanol, acetone, and ethyl acetate. For one-hour ultrasonic extraction with solvent of ethyl acetate, the favorable content of glabridin was obtained as 1.26g/kg. The glabridin was well separated in the mobile phase composition of 50/50 vol. % (acetonitrile/water).

• Journal of the Korean Chemical Society
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• v.32 no.2
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• pp.113-121
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• 1988

The retention mechanism and separation of various aromatic sulfonic and carboxylic acids on reversed-phase liquid chromatographic column were studied in the mobile phase containing dodecyltrimethylammonium bromide (DTAB). The retention mechanism was found to be followed the ion-interaction model where the DTAB occupies a primary layer at the stationary phase while the sample anions and other co-anions in the system compete for forming the secondary layer. The capacity factors of samples were influenced by the several factors such as pH, concentration of various organic solvents, co-anions in the mobile phase and functional groups in sample molecules. Some mixtures of organic samples were attempted to separate under optimum condition.

• KSBB Journal
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• v.29 no.4
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• pp.232-238
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• 2014

The simultaneous determination of creatine monohydrate (CrM), dicyandiamide and dihydrotriazine in dietary supplements using reversed-phase high performance liquid chromatography (HPLC) was developed. Chromatography was performed on a Nuclosil 100-5 SA ($4.6{\times}250mm$) column with a mobile phase of 2.3% ammonium phosphate (pH 5.5), and UV detection at 224 nm, 212 nm, and 237 nm, respectively. The performance characteristics of HPLC were determined in terms of selectivity, linearity, precision, recovery, limit of detection (LOD), and limit of quantification (LOQ). The calibration curves were linear within the concentration range of $40.0{\sim}500.0{\mu}g/mL$ for creatine, $0.1{\sim}12.8{\mu}g/mL$ for dicyandiamide, and $0.05{\sim}6.4{\mu}g/mL$ for dihydrotriazine. The detection limits of the method were 1.09, 0.01, and $0.08{\mu}g/mL$ for creatine, dicyandiamide, and dihydrotriazine, respectively. The recoveries of creatine, dicyandiamide, and dihydrotriazine were 97.2~100.9, 92.3~106.5, and 97.2~105.5%, respectively. It is expected that the chromatographic analytical method developed in this study will be usefully applicable to simultaneous determination of creatine, dicyandiamide, and dihydrotriazine contained in dietary supplements.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.283.1-283.1
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• 2003

This study was designed to develop and validate an isocratic reversed phase high performance liquid chromatographic(HPLC) method for the quantitation of sobrerol in drug preparations, and obtain the data pool that can be used in the revision of pharmacopoeia. The separation of sobrerol and the other compounds (S-carboxymethylcysteine, acetaminophen, methyl paraben, propyl paraben, and sobrerol degradants) was achieved in a C18 column with an acetonitrile-methanol-water(24.5:10.5:65.0) mobile phase. (omitted)

• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.432-439
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• 2011

BACKGROUND: An official analytical method was developed to determine etofenprox residues in agricultural commodities using high-performance liquid chromatography (HPLC). METHODS AND RESULTS: The etofenprox residue was extracted with acetone from representative samples of five raw products which comprised rice grain, apple, mandarin, cabbage, and soybean. The extract was then serially purified by liquid-liquid partition and Florisil column chromatography. For rice and soybean samples, acetonitrile/n-hexane partition was additionally coupled to remove nonpolar lipids. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate etofenprox from co-extractives. Intact etofenprox was sensitively detected by ultraviolet absorption at 225 nm. Recovery experiment at the quantitation limit validated that the proposed method could apparently determine the etofenprox residue at 0.02 mg/kg. Mean recoveries from five crop samples fortified at three levels in triplicate were in the range of 93.6~106.4%. Relative standard deviations of the analytical method were all less than 10%, irrespective of crop types. A selected-ion monitoring LC/mass spectrometry with positive atmospheric-pressure chemical ionization was also provided to confirm the suspected residue. CONCLUSION(s): The proposed method is simple, rapid and sensitive enough to be employed in routine inspection or monitoring of agricultural products for the etofenprox residue.

• Journal of the Korean Chemical Society
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• v.42 no.2
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• pp.197-202
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• 1998

1-(2-Pyridylazo)-2-Naphthol (PAN) has been widely used as a spectrophotometric reagent and metallochromic indicator for many metal ions. In this work, the chelate reagent of PAN was used as mobile phase additive for the separation of metal ions by reversed phase chromatography. Metal ions could be detected by monitoring the effluent at 570 nm with spectrophotometric detector. In order to investigate retention behaviors of the metal ions, the chromatograms and capacity factors were obtained as the variation of pH, ionic strength and composition of organic modifier in mobile phase. Under the obtained optimum conditions, the mixtures of Fe(III), Ni(II), Cu(II), Zn(II) and Co(II) could be separated successfully and the calibration curves under the recommended conditions showed an excellent linearity. The detection limits(S/N) were feasible at the nanogram level.

• Analytical Science and Technology
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• v.8 no.4
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• pp.519-527
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• 1995

The retention mechanism of Ni(II)-${\alpha}$-isonitroso-${\beta}$-diketone imine chelates in reversed-phase HPLC has been studied by examining the effect of temperature, mobile phase composition in acetonitrile-water mixture, and molecular structure on retention. The empirical retention equation was investigated to evaluate the properties of S (hydrophilic index). The value of the S index of the Ni(II) chelates decrease with the increasing column temperature and a linear relationship between S and log $k{_w}^{\prime}$ has been found. The results showed that the S index is influenced by the interaction between Ni(II) chelates and mobile phase. Molecular properties, van der Waals molar volume, polarizability and dipole moment, of the Ni(II) chelates were calculated by Cerius 2 program and the calculations were performed at Universal Force Field (UFF) model. The S value and log $k{_w}^{\prime}$ increase with decreasing the dipole moment of Ni(II) chelates.

• Journal of the Korean Chemical Society
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• v.47 no.6
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• pp.547-552
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• 2003

Separation and determinations of Co(II) and Ni(II) ions as their 4-(2-pyridylazo)resorcinol(PAR) chelates by reversed-phase capillary high-performance liquid chromatography(RP-CpHPLC) were performed. Among many capillary columns, Vydac C4 column was selected and acetonitrile solution was used as mobile phase. The effect of pH and MeCN concentration(%) on the retention factor, k and peak intensity was examined and discussed. As a results, it was found that 22.5% MeCN and pH 5.60 was adequate as mobile phase for the separation of the two metal ions and determination of Co(II) ion, but the mobile phase condition for Ni(II) ion determination was 22.5% MeCN of pH 7.20. Detection limit(D.L., S/N=3) of Co(II) and Ni(II) ions were $2.0{\times}10{-7}$ M(14.9 ppb) and $1.0{\times}10{-6}$ M(59.2 ppb), respectively.

• Bulletin of the Korean Chemical Society
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• v.7 no.1
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• pp.45-50
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• 1986

Separation of optical isomers of some derivatives of amino acids by reversed-phase HPLC has been accomplished by adding a chelate of an optically active amino acid to copper(Ⅱ) to the mobile phase. Cu(Ⅱ) complexes of L-proline and L-hydroxyproline in the mobile phase showed different degrees of separation. Optical isomers of DNS derivatives of amino acids are selectively separated, but those of several other derivatives are not at all. The kinds of buffer agents, the pH, and the concentrations of acetonitrile and the Cu(Ⅱ) ligand all affect the separations. The elution behavior between D and L DNS-amino acids appears to depend on the alkyl side chain of the amino acids. A chromatographic mechanism is proposed that is based on a stereospecificity of the formation of ternary complexes by the D, L-DNS-amino acids and the chiral additive associated with the stationary phase. The steric effects of the ligand exchange reactions are related with the feasibility of cis and/or trans attack of the amino acids to the binary chiral chelate retained on the stationary phase.