• Korean Journal of Medicinal Crop Science
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• v.10 no.3
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• pp.200-205
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• 2002

Platycodin D was isolated from n-butanol extract of Platycodi radix(Platycodon grandiflorum and identified by the spectroscopic analysis using $^1H$ and $^{13}C$ NMR techniques. A new method of analysis of platycodin D by high performance liquid chromatography(HPLC) was established using a reversed phase system with YMC-Pack ODS-AM( 250 X 4.6 mm) column and 30% acetonitrile as a mobile phase. Evaporative light scattering detector was used as detector. The kinds of extraction solvents and methods were examined to determine the efficient extraction condition and HPLC analysis was carried out to establish the optimum drying condition for the root of Platycodon grandiflorum. The contents of Platycodin D was highest as 0.083% when platycodon roots were dried at $60^{\circ}C$ using dry oven.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.4100-4105
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• 2013

The Peanut sprouts have been used as food for long time in many Asian countries. Among them, resveratrol have bioactivity effects as antioxidant and anticancer. In this work, resveratrol was extracted from peanut sprouts by dipping(extraction time 3h, $25^{\circ}C$) method. And extraction efficiency and amount was identified using on-line screening HPLC-ABTS. From the experimental results, it is evident that the amount of resveratrol($0.310-0.346{\mu}g/mL$) by 50% aqueous EtOH was higher than any 100% water and EtOH composition. Also, the 100% water extracts sample was low yield 2.040-2.145%. The shown results can be applied as sources for pharmaceuticals and functional material.

• YAKHAK HOEJI
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• v.53 no.5
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• pp.281-285
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• 2009

The retention of solutes in reversed-phase high-performance liquid chromatography depends on their hydrophobicity. Although the retention behaviors of alkyl benzenes have been reported so far, quite a few authors have mentioned the retention behavior of alkyl benzenes with plural hydrophobicity parameters. In this sense, we were interested in the retention behaviors of alkyl benzenes having benzene moiety and increasing alkyl chain. In this study, we therefore investigated the retention behavior of alkyl benzenes in reversed-phase high-performance liquid chromatography in order to obtain information concerning the effects of the aromatic moiety and the carbon chain on the retention mechanism by comparing their capacity factor (k') in relation to the carbon chain length. The eluent acetonitrile ($CH_3CN$) showed high selectivity on alkyl benzenes, showing the high difference of capacity factor (${\Delta}log\;k'$) between toluene and octyl benzene. Indeed, the ${\Delta}log\;k'$ of 80% $CH_3CN$ represented 1.42- and 4.25-times longer than 90% MeOH and 60% THF, respectively. The hydrophobicity parameters, van der Waals volume, bond constant, partition constant, $\pi$-energy effect and enthalpy were evaluated with the capacity factor (k') of alkyl benzenes eluted on 80% CH3CN, 90% MeOH and 60% THF, respectively. The best eluent for predicting retention behavior of alkyl benzenes was 90% MeOH ($R^2$ 0.999). The three parameters, van der Waals volume, bond constant and partition constant were well coincident to log k' by increasing alkyl benzenes. However, $\pi$-energy effect and enthalpy were severely disagreeable. Taken together, van der Waals volume, bond constant and partition constant were a reliable parameters to predict the retention behaviors of alkyl benzenes on reversed-phase column.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.656-662
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• 1999

We have obtained retention data of benzene, toluene, ethylbenzene, phenol, and acetophenone at 25, 30, 35, 40, 45 and 50 $^{\circ}C$ in 30/70, 40/60, 50/50, 60/40, 70/30, and 80/20 (v/v %) methanol/water eluents using a $C_18$ phase with a high ligand density. We drew van't Hoff plots from the data, and computed enthalpies and entropies of solute transfer from the mobile to the stationary phase. The cavity formation effect was found the major factor that governs the solute distribution between the mobile and stationary phases. The hydrophobic effect became significant in highly aqueous mobile phases. We also concluded that the Shodex C18-5B stationary phase was a polymer-like phase with a high ligand density, and followed a partially adsorption-like mechanism.

• Korean Chemical Engineering Research
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• v.47 no.2
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• pp.258-261
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• 2009

In this work, we the ettect on extraction amounts and general composition content of phytoestrogen genistein and formononetin extracted from Sophoraflavescens Aiton by various ultrasonic waves(35, 72, and 170 KHz) and extraction time(30, and 60 min) were compared using extraction solvent water 100%. The pretreatment step was composed of ultrasonic waves extraction, filtration, concentration, and membrane filtration. The extracted sample was analyzed by reversed-phase high performance liquid chromatography(RP-HPLC). And the mobile phase applied was linearly changed with A/B of 80/20~65/35 vol% for 60 min(A water/acetic acid, 99.9/0.1 vol%, B acetonitrile/acetic acid, 99.9/0.1 vol%). The experimental results, general composition carbohydrate(0.255 to 0.413%) excepts, other ingredients was confirmed almost similarly. Also, The highest yield of extraction amount 3.17g was obtained by ultrasonic waves with a frequency of 170 KHz and an extraction time of 60 min. This work offers would be useful for chemical and biological studies of natural plants and its products.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1248-1258
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• 2010

In this paper, a method for simultaneously realizing the sum and difference patterns which are required in the monopulse radar sensor systems, is presented by using single taper array antenna with rectangular microstrip patches. The widths of patches are first determined by the voltage weights which are synthesized for the fundamental array factor patterns to be applied to the monopulse operation by using the sidelobe levels(SLLs) control technique. As the bi-directionally series-fed technique is applied and the lengths of connecting lines between patches are appropriately adjusted, the single array generates two phase-shifted beams which activates out-of-phase and in-phase ports of a $180^{\circ}$ hybrid coupler to synthesize the sum and difference patterns. The simulated results on the configuration designed at 9.5 GHz are compared with measured results showing the validity of the proposed method.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.403-409
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• 1997

The equilibrium constants of five deoxyribonucleosides (dDyd, dUrd, dGuo, dThd, dAdo) were estimated by the plate theory and the moment method under isocratic conditions of the Reversed-Phase High Performance Liquid Chromatography (RP-HPLC). The mobile phase in this system was composed of water and organic modifiers(acetonitrile and methanol) The plate theory of linear adsorption isotherm was treated on the basis of continuous flow of eluent through the plates of the column. The moment method was utilized to find the equilibrium constant from the first absolute moment of experimental data. The equilibrium constants of five deoxyribonucleosides in the two methods were very close, and also the equilibrium constants calculated by capacity factor were similar to those by both the plate theory and the moment method. The equilibrium constant was expressed as a semi-log function of the quantity of organic modifier. Excellent agreements between the calculated elusion profile by the plate theory and the experimental data were observed.

• The Korean Journal of Food And Nutrition
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• v.16 no.3
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• pp.165-170
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• 2003

A sensitive and accurate method for the detection of astaxanthin was developed. The optimum HPLC system for the extraction and quantification of astaxanthin was based on a reversed phase column, and a quaternate mobile phase contained dichloromethane. The amount of astaxanthin can be accurately quantified in Phaffia rhodozyma cultures. The results of this study suggest that the mixture solution of dimethylsulphoxide and acetone is the optimal extraction solvent for astaxanthin and samples treatment for astaxanthin analysis must control low temperature and absent light operation strictly.

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.216-223
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• 1986

Separation of optical isomers of DNS derivatized amino acids by a reversed-phase high-performance liquid chromatography has been studied by adding a complex of an optically active amino acid (L-arginine) with the metal ion (Cu(II), Zn(II), Cd(II), Ni(II)) to the mobile phase. The separations are affected by the concentrations of acetonitrile, chelate and buffer. They are also affected by the pH and the kinds of metal and buffer. A separation mechanism, which is based on steric effect of the ligand exchange reaction for the formation of ternary complexes by the D,L-DNS-amino acids and the chiral additive associated with the stationary phase, is proposed to interpret the elution behaviors of D, L-dansyl-amino acids.

• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.720-724
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• 1991

Simultaneous determination of chloragenic acid (CA), 3,4-o-dicafeoyl quinic acid(3,4-DCQA), 4,5-o-dicaffeoyl quinic acid (4,5-DCQA) and linarin in Chrysanthemum sibiricum Fisher was newly established by a reversed-phase high performance liquid chromatography (HPLC). Sample was extracted with 20 ml methanol for 4 hrs. The extract was cleaned up by using Sep-Pak $C_18$ cartridge and 4 ml methanol-$H_2$O(1 : 1) as eluent. Their determination was performed by means of RP-HPLC with Bondapak $C_18$ column (30 cm ${\times}$ 3.9 mm i.d., 10 ${\mu}m$ and gradient elution mode as methanol-5 mM $H_3PO_4$ solution (30 : 70). The established method was applied to various samples purchased. As a result, their content ranges showed to be 0.35~0.55% for CA, 0.46~0.76% for 3,5-DCQA, 0.077~0.23% for 4,5-DCQA and 0.16~2.72% for linarin, respectively.