• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.945-947
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• 2009

• Bulletin of the Korean Chemical Society
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• v.26 no.2
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• pp.297-302
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• 2005

The determination of total phenols was accomplished by capillary-high performance liquid chromatography (capillary-HPLC) after nitrosation of the U.S.E.P.A. classified 11 priority pollutant phenols, using the nitrosated parent phenol (POHNO) as a reference for calibration. The optimum mobile phase composition for this analysis was found by examining the effect of changing the percentage of acetonitrile (MeCN) in the mobile phase on retention factors (k values) and peak intensities. As MeCN percentage was increased, k values were reduced and peak intensities were generally increased. From the results obtained, it was found that the optimum mobile phase was 90%(v/v) MeCN solution at pH 8.0, the detection wavelength of 400 nm, and a detection limit (D.L., concentration at signal to noise ratio (S/N) of 3.0) of 4.5 ${\times}$ $10^{-7}$ M. In addition, 10 of the 11 phenols present in mineral or waste water were separated after the nitrosation by capillary-HPLC. The optimum mobile phase for separation was a 40%(v/v) MeCN solution at pH 5.0.

• Korean Journal of Food Science and Technology
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• v.37 no.4
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• pp.513-518
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• 2005

Capillary electrophoresis (CE) method was developed to determine (+)-catechin and (-)-epicatechin contents in grape seed ethanol extract. CE separation was achieved using 100 mM phosphate and borate buffer at pH 6.0 as background electrolyte and fused silica capillary with 50 microns x 375 microns O.D. (effective length 20.0cm) maintained at $25^{\circ}C$. The applied voltage was 10kV, and detection was performed by DAD at 210 nm, Two catechins were well separated within 6 min with repeatability of <0.8% RSD for migration time and <2.0% RSD for peak area, and correlation coefficients higher than 0.994 were obtained from 58.0 to 174.0 mg/L with detection limit of 0.035 mg/L. Separated compounds were successfully determined. CE method was easy to handle and showed good reproducibility. CE method was compared with conventional coloring and HPLC methods, and main advantages of CE method were low amount of sample required, simple pre-sample treatment, good recovery rate, and short analysis time.

• Archives of Pharmacal Research
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• v.29 no.9
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• pp.808-813
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• 2006

Two methods for the chiral purity determination of bevantolol were developed, namely capillary electrophoresis (CE) using carboxymethyl-${\beta}$-cyclodextrin (CM-${\beta}$-CD) as a chiral selector and high-perfomance liquid chromatography (HPLC) using a chiral stationary phase. In the HPLC method, the separation of bevantolol enantiomers was performed on a Chiralpak AD-H column by isocratic elution with n-hexane-ethanol-diethylamine (10:90:0.1, v/v/v) as mobile phase. In the CE method, bevantolol enantiomers were separated on an uncoated fused silica capillary with 50 mM amonium phosphate dibasic adjusted to a pH 6.5 with phosphoric acid containing 15 mM CM-${\beta}$-CD as running buffer. Validation data such as linearity, recovery, detection limit, and precision of the two methods are presented. The detection limits of S-(-)-bevantolol were 0.1% and 0.05% for CE and HPLC method, respectively and R-(+)-bevantolol were 0.15% and 0.05% for CE and HPLC method, respectively. There was generally good agreement between the HPLC and CE results.

• YAKHAK HOEJI
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• v.43 no.4
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• pp.429-436
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• 1999

A simple, accurate and reproducible Capillary electrophoresis (CE) assay has been developed for the determination of baicalin, baicalein, wogonin and chrysin in Scutellaria baicalensis. Successful separation of these compounds has been obtained in 35 mM phosphate butter (pH 7.0) using a untreated fused silica capillary ($57{\;}cm{\times}75{\;}{\mutextrm{m}}$ i.d.) at $25^{\circ}C$ with the electric field of 19kV. Baicalin, baicalein wogonin and chrysin was separated and detected at 280 nm 13 min. The detection limits of CE were acceptable compared to HPLC. Reproducibilities of migration time and peak area were 0.66~1.11% (within-run), 2.18~3.38% (between-run) and 3.50~4.55% (within-run), 3.97~4.82%(between-run) at CE. The results indicate that CE could be a promising technique for quality and quantity control analysis of Scutellaria baicalensis as a validation method.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2666-2670
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• 2011

High-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) were used to identify five active components in the modified herbal decoction Bo-Yang-Hwan-O-Tang (mBHT), i.e., amygdalin, decursin, paeoniflorin, salvianolic acid B, and calycosin-7-O-${\beta}$-D-glycoside. These components were identified by comparing their retention times and mass spectra with those of reference compounds. The conditions of both analytical methods were optimized and validated. Sufficient separation of target analytes was achieved using a buffer consisting of 40 mM sodium borate and 60 mM sodium dodecylsulfate (SDS) containing 10% methanol (pH 9.5) at 250 nm for CE analysis and gradient elution with a water-methanol mobile phase and ultraviolet (UV) photodiode array detector (DAD) at 250 nm for HPLC analysis. The mBHT components were determined within 65 min by HPLC and 16 min by CE. All calibration curves showed high linearity (R > 0.999) within the ranges tested. Intra-day and inter-day precision were less than 1.6% and 1.8% for HPLC and 2.5% and 4.8% for CE, respectively. The accuracy of the methods ranged from 98.8% to 102.3% for HPLC and from 95.9% to 108.2% for CE.

• Bulletin of the Korean Chemical Society
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• v.24 no.12
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• pp.1781-1784
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• 2003

Determination of Co(II) ion as a 4-(2-thiazolylazo)resorcinol(TAR) or 5-methyl-4-(2-thiazolylazo)resorcinol(5MTAR) chelate was accomplished by reversed-phase capillary high-performance liquid chromatography (RP-Capillary-HPLC) using a Vydac $C_4$ column and MeCN-water mixture as mobile phase. The effect of change in pH and MeCN percentage of the mobile phase on the retention factor, k and peak intensity were evaluated. It was found that 30% MeCN (v/v) of pH 5.60 or 7.20 was adequate as mobile phase when TAR or 5MTAR is used. Detection limit (D.L., S/N=3) in each case was $2.0\;{\times}\;10^{-7}$M (11.8 ppb) and $3.0\;{\times}\;10^{-7}$ M (17.7 ppb). The Co(II) ion in mineral and waste water was determined with the optimum column and mobile phase.

• 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.

• Journal of Integrative Natural Science
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• v.9 no.1
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• pp.28-34
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• 2016

A number of chiral selectors have been developed and applied for enantiomer separation of a variety of chiral compounds. Among these chiral selectors are chiral crown ethers, a class of synthetic host polyether molecules that bind protonated chiral primary amines with high selectivity and affinity. In this paper, two important chiral crown ethers as chiral selectors of bis-(1,1'-binaphthyl)-22-crown-6 and (18-crown-6)-2,3,11,12-tetracarboxylic acid (18-C-6-TA) are focused. They have been widely used to resolve the enantiomers of chiral compounds containing a primary amino moiety using chiral stationary phases (CSPs) or chiral selectors by high-performance liquid chromatography (HPLC), capillary electrophoresis (CE) and so on in chirotechnology. Also, it was described that the commercially available covalent type HPLC CSPs derived from (+)- and (-)-18-C-6-TA have been developed and successfully applied for the resolution of various primary amino compounds including amino acids.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.3114-3114
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• 2001

During the last years phytochemistry and phytopharmaceutical applications have developed rapidly and so there exists a high demand for faster and more efficient analysis techniques. Therefore we have established a near infrared transflectance spectroscopy (NIRS) method that allows a qualitative and quantitative determination of new polyphenolic pharmacological active leading compounds within a few seconds. As the NIR spectrometer has to be calibrated the compound of interest has at first to be characterized by using one or other a combination of chromatographic or electrophoretic separation techniques such as thin layer chromatography (TLC), high performance liquid chromatography (HPLC), capillary electrophoresis (CE), gas chromatography (GC) and capillary electrochromatography (CEC). Both structural elucidation and quantitative analysis of the phenolic compound is possible by direct coupling of the mentioned separation methods with a mass spectrometer (GC-MS, LC-MS/MS, CE-MS, CEC-MS) and a NMR spectrometer (LC-NMR). Furthermore the compound has to be isolated (NPLC, MPLC, prep. TLC, prep. HPLC) and its structure elucidated by spectroscopic techniques (UV, IR, HR-MS, NMR) and chemical synthesis. After that HPLC can be used to provide the reference data for the calibration step of the near infrared spectrometer. The NIRS calibration step is time consuming, which is compensated by short analysis times. After validation of the established NIRS method it is possible to determine the polyphenolic compound within seconds which allows to raise the efficiency in quality control and to reduce costs especially in the phytopharmaceutical industry.