• Journal of the Korean Chemical Society
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• v.37 no.12
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• pp.1035-1046
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• 1993

Some iron(III)porphyrin complexes were prepared, and identified by the spectroscopic methods. Elution behavior of iron(III)porphyrin complexes was investigated by reversed-phase HPLC. The optimum conditions for the separation of iron(III)porphyrin complexes were examined with respect to flow rate and mobile phase strength. These complexes were successfully separated on NOVA-PAK $C_{18}$ column using methanol / water(95/5) for $[T_pCF_3PP)Fe(R)]$ and methanol / water (98/2) for $[(P)Fe(C_6F_5)]$ as a mobile phase. It was found that these complexes were largely eluted in an acceptable range of capacity factor value ($0{\leq}logk'{\leq}1$). The dependence of the capacity factor (k') on the volume fraction of water in the binary mobile phase as well as the dependence of k' on the liquid-liquid extraction distribution ratio$(D_c)$ in methanol-water / n-pentadecane extraction system showed a good linearity. It means that the retention of iron(III)porphyrin complexes on NOVA-PAK $C_{18}$ column is largely due to the solvophobic effect. Also, there was a good linear dependence of the capacity factor(k') on the column temperature and enthalpy calculated by van't Hoff plot. From these results, it was confirmed that the retention mechanism of iron(III)porphyrin complexes in reversed-phase liquid chromatography was invariant under the condition of various temperature, and the solvophobic binding process exhibited isoequilibrium behavior.

• 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.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.315-319
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• 1997

In this study, the optimum analytical conditions for determination of distribution of propylene oxide in a nonionic surfactant and separation of fatty alcohols were investigated by Reversed Phase High Performance Liquid Chromatography. To analyse the distribution of propylene oxide (PO) and carbon chain length of a fatty alcohol, we derivatized samples for the purpose of using a UV detector. Also, we studied the influences of columns and mobile phase composition to obtain the optimum separation conditions. In our experiment, Waters Symmetry $C_8(3.9{\times}150mm)$ column was used. And the optimum condition were obtained by gradient elution with methanol and water as the mobile phase. In the plot of log k' vs composition of water in the binary phase, the linerality was very good. We ploted the calibration curve to conform the quality of fatty alcohol, a good linerality was obtained.

• 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.

• FOCUS: LIFE SCIENCE
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• no.1
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• pp.3.1-3.7
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• 2024

The article discusses the critical role of chromatography in the analysis and purification of proteins in biopharmaceuticals, emphasizing the importance of comprehensive characterization for ensuring their safety and efficacy. It highlights the use of Avantor® ACE® HPLC columns for the separation and purification of proteins, focusing on the analysis of intact proteins using reversed-phase liquid chromatography (RPLC) with fully porous particles. This article also details the application of different mobile phase additives, such as TFA and formic acid, and emphasizes the advantages of using type B ultra-pure silica-based columns for efficiency and peak shape in biomolecule analysis. Additionally, it addresses the challenges of analyzing intact proteins due to slow molecular diffusion and introduces the concept of solid-core (or superficially porous) particles, emphasizing their benefits over traditional porous particles for the analysis of therapeutic proteins. Furthermore, it discusses the development of Avantor® ACE® UltraCore BIO columns, specifically designed for the high-efficiency separation of large biomolecules, such as proteins, and demonstrates their effectiveness in achieving high-resolution separations, even for higher molecular weight proteins like monoclonal antibodies (mAbs). In addition, it underscores the complexity of analyzing and characterizing intact protein biopharmaceuticals, requiring a range of analytical techniques and the use of wide-pore stationary phases, operated at elevated temperatures and with relatively shallow gradients. It highlights the comprehensive range of options offered by Avantor® ACE® wide pore columns, including both fully porous and solid-core particles, bonded with a variety of complementary stationary phase chemistries to optimize selectivity during method development. The use of ultrapure and highly inert base silica is emphasized for enabling the use of lower concentrations of mobile phase modifiers without compromising analyte peak shape, particularly beneficial for LC-MS applications. Then the article concludes by emphasizing the significance of reversed-phase liquid chromatography and its compatibility with mass spectrometry as a valuable tool for the separation and analysis of intact proteins and their closely related variants in biopharmaceuticals.

• Bulletin of the Korean Chemical Society
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• v.12 no.5
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• pp.490-494
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• 1991

The ${\beta} to {\alpha}$ phase transition in silver iodide is studied with the (N, V, E) and (N, P, T) molecular dynamics (MD) method. In experiments, the phase transition temperature is 420 K. Upon heating of ${\beta}$ form, the iodine ions undergo hcp to bcc transformation and silver ions become mobile. MD simulations for the ${\beta}$ and ${\alpha}$ phases are carried out at several temperatures and the radial distribution functions (rdf) are obtained at those temperatures in the (N, V, E) ensemble. But the phase transition is not found in our calculation. Next the phase transition is studied with the (N, P, T) MD and we find some evidences of phase transition. At 3 Kbars and 2 Kbars the phase transition temperatu re is about 300 K. For 3.55 Kbars, the phase transition is higher (420 K) than the low pressure case. The phase transition temperature is somewhat dependent on the pressure in our calculations.

• Journal of Ginseng Research
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• v.32 no.4
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• pp.390-396
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• 2008

For evaluating the quality of ginseng, simple and fast analysis methods are needed to determine the ginsenoside content of the ginseng products. The aim of this study was therefore to optimize conditions for fast analysis of the ginsenosides, the active ingredients in extracts of Korean red ginseng. When tandem HPLC mass spectrometry (HPLC-MS/MS) was used, four forms of ginsenoside, Rb1, Rb2, Rc, and Re, were readily separated in seven minutes using a gradient mobile phase (acetonitrile and water containing acetic acid). This is the shortest separation time reported among the studies of major ginsenoside analysis. When gradient HPLC with UV detection was used, the detection limit was high, but separation of these four ginsenosides required 25 minutes using acetonitrile and water containing formic acid as a mobile phase. HPLC-MS/MS was able to separate ginsenoside Rg1 easily regardless of the mobile phase condition, but the HPLC-UV could not separate Rg1 because acetonitrile concentration in the mobile phase had to be maintained below 20%. Ginsenoside peaks were clearer and had more sensitive detection limits when Korean red ginseng extract was analyzed by the HPLC-MS/MS, but the UV detection was useful for chromatographic fingerprinting of all four major ginsenosides of the extract: Rb1, Rb2, Rc, and Re. Extracts were found to contain 2.17 mg, 1.51 mg, 1.29 mg, and 0.46 mg of ginsenoside Rb1, Rb2, Rc, Re, respectively, per gram weight. The ratios of each ginsenoside in the extracts were 1.0 : 0.7 : 0.6 : 0.2, respectively. Taken together, the results indicate that HPLC-MS/MS spectrometry could be the most useful method for rapid analysis of even small amounts of major ginsenosides, while HPLC with UV detection could also be used for rapid analysis of major ginsenosides and for quality control of ginseng products.

• Journal of the Korea Society of Computer and Information
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• v.20 no.4
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• pp.17-23
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• 2015

In this paper, we propose a mobile app clustering method using word clusters. Considering the quick change of mobile app trends, the proposed method divides the mobile apps into some semantically similar mobile apps by applying a clustering algorithm to the mobile app set, rather than the predefined category system. In order to alleviate the data sparseness problem in the short mobile app description texts, the proposed method additionally utilizes the unigram, the bigram, the trigram, the cluster of each word. For the purpose of accurately clustering mobile apps, the proposed method manages to avoid exceedingly small or large mobile app clusters by using the word clusters. Experimental results show that the proposed method improves 22.18% from 57.48% to 79.66% on overall accuracy by using the word clusters.

• YAKHAK HOEJI
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• v.31 no.2
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• pp.112-115
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• 1987

Gypsogenin was derivatized with 2, 4-dinitrophenylhyclrazine prior to analysis with HPLC. Reversed-phase column (Du pont ODS) was used and the mobile phase was acetonitrile and water (60:40). The effluent was detected at 550nm using an U.V. detector and the retention time was approximately 9.2min. The concentration was quantitated by measuring the area and the detection limit was 0.2$\mu\textrm{g}$.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.395.3-396
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• 2002

A simple, rapid and reliable high performance liquid chromatography (HPLC) method has been developed for the measurement of lansoprazole in human plasma, and the application of pharmacokinetic study has been evaluated. Omeprazole was used as an internal standard. After adding methyl tert-butyl ether, samples were stored at －7$0^{\circ}C$. The extracts were easily obtained only with pouring the organic phase. The mobile phase was prepared using acetonitrile and water at the volume ratio of 38:62. (omitted)