• 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.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1941-1945
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• 2008

A new chromatographic stationary phase has been prepared by cross polymerization between allylsilica and perallyloxycucurbit[6]uril and characterized by elemental analysis and FT-IR spectroscopy. The double endcapping has been proven to improve the separation efficiency of the cucurbituril-based stationary phase material. The first end-capping was carried out when allylsilica was made. The second end-capping was done as the final step of the whole process, and the use of a mixture of hexamethyldisilazane (HMDS) and trimethylchlorosilane (TMCS) as an end-capping reagent was found better than the use of only HMDS or TMCS. Our stationary phase has shown generally good results in separation of nonpolar and polar analytes. This phase showed even better separation performance than the commercial C18 phase for the case where hostguest chemistry was properly incorporated in solute retention.

• Bulletin of the Korean Chemical Society
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• v.32 no.10
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• pp.3597-3602
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• 2011

A simple and rapid analytical method was developed for the determination of eight isoquinoline alkaloids in Corydalis species. Eight isoquinoline alkaloids, including 2 aporphine alkaloids (isocorydine and glaucine) and 6 protoberberine alkaloids (coptisine, palmatine, berberine, canadine, corydaline, and tetrahydrocoptisine) were used as chemical markers which have a various biological activity and determined for quality control of Corydalis (C.) species (C. ternata, C. yanhusuo, and C. decumbens). To evaluate the quality of these herbal medicines, LC chromatographic separation of alkaloids were preferentially investigated on reversed-phase C18 column with pH variation and composition of mobile phase. In addition, the separation of these alkaloids in herbal extracts was found to be significantly affected on mobile phase composition using gradient elution. Especially for C. yanhusuo extract, berberine was seriously interfered with other alkaloid extracted from sample matrix when mobile phase composition was not optimized. As results, these compounds were successfully separated within 28 min using 10 mM ammonium acetate containing 0.2% triethylamine (adjusted at pH 5.0) as a mobile phase with gradient elution. On the basis of optimized HPLC conditions, 23 different Corydalis species samples were analyzed for the determination of alkaloid levels. In addition, principal component analysis (PCA) combined with the chromatographic data could be successfully classified the different geographic origin samples.

• Bulletin of the Korean Chemical Society
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• v.28 no.11
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• pp.1980-1984
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• 2007

An HPLC chiral stationary phase (CSP) which has only two ureide functional groups was prepared starting from (1S,2S)-1,2-diaminocyclohexane. The CSP was successful in the resolution of various N-(3,5- dinitrobenzoyl)-α-amino acids, the separation (α) and the resolution factors (RS) being within the range of 1.11-1.35 and 2.19-5.17, respectively with the use of 20% 2-propanol in hexane containing 0.1% trifluoroacetic acid as a mobile phase. However, ethyl esters of N-(3,5-dinitrobenzoyl)-α-amino acids were not resolved or resolved with only marginal separation and resolution factors on the CSP under the identical mobile phase condition. From these results, the complexation of the carboxylate anions of analytes inside the double-ureide pocket of the CSP was expected to play some important role for the chiral recognition. In contrast, N-(3,5- dinitrobenzoyl)-α-amino acid N-propylamides were resolved on the CSP with reasonable separation and resolution factors. Enantioselective hydrogen bonding interactions between analytes and the CSP were presumed to be responsible for these resolutions.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.812-818
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• 2024

The volume and toxicity of radioactive waste can be decreased by separating the components of high-level liquid waste according to their properties. An impregnated silica-based adsorbent was prepared in this study by combining N,N,N',N',N",N"-hexa-n-octylnitrilotriacetamide (HONTA) extractant, N',N'-di-n-hexyl-thiodiglycolamide (Crea) extractant, and macroporous silica polymer composite particles (SiO₂-P). The performance of platinum-group metals adsorption and separation on prepared (HONTA + Crea)/SiO₂-P adsorbent was then assessed together with that of co-existing metal ions by batch-adsorption and chromatographic separation studies. From the batch-adsorption experiment results, (HONTA + Crea)/SiO₂-P adsorbent showed high adsorption performance of Pd(II) owing to an affinity between Pd(II) and Crea extractant based on the Hard and Soft Acids and Bases theory. Additionally, significant adsorption performance was observed toward Zr(IV) and Mo(VI). Compared with studies using the Crea extractant, the high adsorption performance of Zr(IV) and Mo(VI) is attributed to the HONTA extractant. As revealed from the chromatographic experiment results, most of Pd(II) was recovered from the feed solution using 0.2 M thiourea in 0.1 M HNO₃. Additionally, the possibility of recovery of Zr(IV), Mo(VI), and Re(VII) was observed using the (HONTA + Crea)/SiO₂-P adsorbent.

• KSBB Journal
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• v.9 no.1
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• pp.35-39
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• 1994

Separation of pure fructo-oligosaccharides from the mixed solution of glucose, sucrose and fructo-oligosaccharides was studied using a cationic ion-exchange resin column. Optimum separation conditions, i.e., temperature, feeding rate and the ratio of column vs. diameter were evaluated, which were found to be $85^{\circ}C$, $0.25h^{-1}$ and 30, respectively. At the optimized separation conditions, high-purity fructo-oligosaccharides up to 96% were obtained and the total recovery yield was about 66% after four cycles. After the chromatographic separation, purification to remove the salts and color in pure fructo-oligosaccharides solution was successfully conducted using the mixed-bed of cationic and anionic ionexchange resin columns.

• Journal of Pharmaceutical Investigation
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• v.23 no.3
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• pp.133-137
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• 1993

A high-performance liquid chromatographic assay using ion-pair reverse-phase system was developed for the separation of acebutolol and acebutolol acetyl metabolite in plasma. A ion-pair reversephase system consisting of an ODS-bonded silica column and a mixture of 20% $CH_3CN$, 0.1% $H_3PO_4$, 0.035 M heptanesulfonic acid and 0.005 M tetrabutylammonium hydrogen sulfate as the mobile phase were used. Triamterene was employed as an internal standard. Based on 0.2 ml of plasma, the detection limits were 10.4 ng/ml for acebutolol and 10.3 ng/ml of acebutolol acetyl metabolite at the signal-to-noise ratio of 3:1.

• Analytical Science and Technology
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• v.8 no.4
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• pp.859-864
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• 1995

Mono- and oligosaccharides are derivatized with p-aminobenzoic ethyl ester (ABEE), strongly absorbs UV light at 254 nm, in the presence of sodium cyanoborohydride. C18-bonded silica column is used for the separation of sugar-ABEE derivatives in an isocratic mode. RP-HPLC conditions are optimized by using ternary mixture as mobile phase and $45^{\circ}C$ as a column temperature. Sugar-ABEE derivatives are separated well within a short run time (ca. 25 min) by reverse-phase partition chromatographic mode. The ($1{\rightarrow}6$) linkage type of dihexose-ABEE derivatives has shorter retention time than ($1{\rightarrow}4$)-linkage type. After acid hydrolysis of glycoproteins with 2M trifluoroacetic acid, monosaccharide composition and contents are determined. This procedure is very useful for the simultaneous analysis of neutral and amino sugars in a single chromatographic step using RP-HPLC without reacetylation of deacetylated amino sugars, which are produced by acid hydrolysis.

• Korean Journal of Clinical Pharmacy
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• v.10 no.1
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• pp.38-41
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• 2000

A high-performance liquid chromatographic method with fluorometric detection was evaluated for analysis of ofloxacin in plasma. Biological fluids (plasma, $200\;{\mu}L$) were prepared for assay by protein precipitation with chlorofurm. The detection of ofloxacin and triamterene as an internal standard were performed at 358 nm for excitation and 495 nm for emission. The HPLC separation was carried out on Ultrasphere ODS column (4.6 mm${\times}25\;cm,\;5\;{\mu} m$) with acetonitrile $(45\%)$-phosphoric acid $(1.5\%)\;containing\;0.3\%$ sodium laurylsulfate as the mobile phase. The flow-rate was 1.0 mL/min. The calibration graphs were linear from 3.0 to 80 ng/mL with r=0.998. The minimal detectable concentration in plasma was 1.5 ng/mL. The proposed technique is reproducible, selective, reliable and sensitive.

• YAKHAK HOEJI
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• v.28 no.4
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• pp.243-248
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• 1984

For gas chromatographic determination with the sulfur-specific flame photometric detector, nine ${\beta}$-lactam antibiotics without ${\alpha}$-amino group were esterified with borontrifluoride-methanol complex and then N-benzoylated with benzoyl chloride. The gas chromatographic separation of these products was successfully carried out on various silicon polymers (OV-1, OV-101, OV-17, OV-225, and QF-1) coated on the acid washed, silanized diatomite. The structure of the esterified and N-benzoylated product was confirmed by mass spectromer.