• Analytical Science and Technology
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• v.23 no.1
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• pp.97-101
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• 2010

(R)-N-3,5-dinitrobenzoyl (DNB) phenylglycinol derived chiral selector was used as a HPLC chiral stationary phase (CSP) for the resolution of racemic N-acylnaphthylalkylamines. In this study, determination of optical purity was performed by both chiral chromatography and NMR spectroscopy by using the (R)-phenylglycinol derived chiral selector. The data of accuracy and precision of each optical purity value are calculated from the results of NMR and HPLC experiments by comparing with true value. Average error of the NMR method was +2.2% with average RSD of 4.54%, while that of HPLC method was -3.5% with average RSD of 3.23%.

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.577-582
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• 2012

In this work, vibrational circular dichroism (VCD) technique was applied for the determination of %EE of chiral compounds. It may provide an easy way to determine the %EE with a proper accuracy within 2% error ranges as well as the absolute configuration of enantiomers. We demonstrated herein a flow cell VCD (FT-VCD) technique for time-dependent %EE measurements. The simultaneous monitoring of the mole fraction and %EE for two chiral species (epichlorohydrin and glycidol mixture) in the mixture was shown to be successful without any further separation steps. Thus, we demonstrate that FT-VCD is an appropriate analytical tool to monitor the kinetics of reactions involving chiral molecules. FT-VCD also provides a convenient nondestructive approach for the time dependent determination of the optical purity of individual components in a reaction mixture containing chiral molecules.

• KSBB Journal
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• v.25 no.5
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• pp.449-452
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• 2010

L-Thyroxine possessing a chiral center, the naturally occurring thyroid hormone has been used for the treatment of thyroid dysfunctions and marketed as levothyroxine (L-thyroxine) sodium salt. In this study, after extraction of levothyroxine tablet as a pre-treatment process, direct enantiomer separation of thyroxine on crown ether derived chiral columns for determination of optical purity was performed using reversed mobile phase with acid additive. The chromatographic method developed in this study was applied in the determination of optical purity of several current domestic and foreign commercialized levothyroxine tablets. Optical purity values of these commercialized L-thyroxine sodium tablets except one were higher than 99 percents.

• Clean Technology
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• v.22 no.2
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• pp.75-81
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• 2016

As the quality of life has improved, the desire for the safety and quality of the foods and drugs has been gradually increasing. For safety and quality management in foods, drugs, health management, agriculture, environmental conservation, and the industrial fields, the demand for quickly and accurately measuring various chemicals has been increasing. As well, the desire for self-diagnosis of one's own health state and self-examining the safety of environment has been gradually increasing. Optical Isomers can have very different physiological effects on human beings. One isomer can exhibit desirable pharmacological, pharmacodynamic, pharmacokinetic and physiological properties, while the other isomer can exhibit undesirable and toxic properties toward living organisms, especially human beings. And they can exhibit different activities in chemical and biotechnological processes. Although the majority of commercially available drugs are now both synthetic and chiral materials, a most chiral drugs are still marketed as racemic drugs. Thus, to avoid possible undesirable side effects from chiral drugs, more effective methods for separating and recognizing chiral compounds are urgently needed. In this report, we investigated the overall developing trends of the chiral drug separation and analysis technology by using molecular recognition.

• Analytical Science and Technology
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• v.24 no.5
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• pp.360-367
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• 2011

Optical purities of 10 commercialized naproxens prepared from eight Korean drug companies were examined by an optimized chiral HPLC condition. The Chiralcel OD-H column and ChiralHyun-LE(S)-1 column were used as chiral stationary phases and the mixed eluent of hexane/isopropanol/acetic acid as 100:2.85:0.1 was used as a mobile phase for effective enantioseparation. Optical purity values of most samples were higher than 97 percents, only one of them was about 95 percents. The average relative standard deviation of them appeared very small (0.034%).

• Analytical Science and Technology
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• v.22 no.2
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• pp.148-151
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• 2009

Enantiomer separation of N-fluorenylmethoxycarbonyl (FMOC) $\alpha$-amino acid was performed on covalently immobilized chiral column (Chiralpak IB) based on polysaccharide derivative as a chiral selector by reversed phase liquid chromatography. The effect of the reversed mobile phase on the chromatographic parameters of the enantioselectivities, resolution factors and retention times using covalently immobilized Chiralpak IB was shown. Also the enantiomer separation of N-FMOC $\alpha$-amino acid in the reversed and normal phase was compared and the results obtained in the former mobile phase were generally lower than those in the latter mobile phase.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.769-776
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• 2008

The stereoselective synthesis of chiral terminal epoxide is of immense interest due to their utility as versatile starting materials as well as chiral intermediates. In this study, new chiral Co(salen) complexes bearing cobalt(II) chloride, iron(III) chloride and zinc(II) nitrate have been synthesized and characterized. The mass and EXAFS spectra provided the direct evidence of formation of complex. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of terminal epoxides such as styrene oxide and phenylglycidylether by hydrolytic kinetic resolution technology and for the synthesis of glycidyl buthylate. The easily prepared complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ nucleophile, providing enantiomerically enriched terminal epoxides (>99% ee). The newly synthesized chiral salen showed remakablely enhanced reactivity with substantially low loadings. The system described in this work is very efficient for the sinthesis of chiral epoxide and 1,2-diol intermediates.

• Journal of the Korean Chemical Society
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• v.46 no.5
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• pp.412-429
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• 2002

Chiral separation of gemifloxacin, an quinolone antibacterial agent, using (+)-(18-crown-6)-tetracar-boxylic acid $(18C6H_4)$ as a chiral selector was performed by capillary electrophoresis (CE). Direct analysis of quinolone antibacterial agent in body fluid is beneficial in terms of fast analysis time, multicomponent analysis. However, high con-centration of sodium ion in body fluid can prevent gemifloxacin from interacting with $18C6H_4$ since sodium ion has high affinity with $18C6H_4$ due to the strong charge interaction. Ethylenediaminetetraacetic acid (EDTA), as a chelating ligand, was added in the running buffer in order to reduce the interaction between sodium ion and the chiral selector. Increased separation efficiency and reduced migration time were observed while sodium ion exists in the sample solution at the concentration up to 150 mM.

• Applied Chemistry for Engineering
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• v.18 no.3
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• pp.218-226
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• 2007

The stereoselective synthesis of chiral terminal epoxides is of immense academic and industrial interest due to their utility as versatile starting materials as well as chiral intermediates. In this study, new dinuclear chiral Co (salen) complexes bearing gallium-, indium- and tallium-chloride have been synthesized and characterized. The mass and EXAFS spectra provided the direct evidence of formation of dinuclear complex. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of various terminal epoxides having ether or ester groups by hydrolytic kinetic resolution technology. The easily prepared dimeric complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ nucleophile, providing enantiomerically enriched terminal epoxides (> 99% ee). The dimeric structured chiral salen showed remarkably enhanced reactivity and may be employed substantially lower loadings than its monomeric analogues. The system described in this work is very efficient for the synthesis of chiral epoxide and 1,2-diol intermediates

• Analytical Science and Technology
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• v.22 no.4
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• pp.313-318
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• 2009

Liquid chromatographic enantiomer separation of amino alcohols was performed on several chiral columns based on polysaccharide derivatives under the mobile phase conditions containing acid or base additive. The chromatographic parameters were greatly influenced by the nature of the mobile phase containing acid or base additive as well as the used chiral columns. Compared to chromatographic results obtained in the mobile phase containing base additive (0.1% triethylamine), especially, Chiralcel OD showed dramatically enhanced separation factors and resolution factors with reduced capacity factors under the mobile phase condition containing acidic additive (0.1% trifluoroacetic acid). When the mobile phase containing 0.05% trifluoroacetic acid and 0.05% triethylamine was used on Chiralcel OD, the greatest separation factors and resolution factors among all other mobile phase conditions in this study were observed.