• Proceedings of the PSK Conference
• /
• 2003.04a
• /
• pp.275.2-276
• /
• 2003

Several ${\beta}$-agonists were investigated for the possible separation of the enantiomers by reversed-phase high-performance liquid chromatography after derivatization with a new chiral derivatization agent, GATC. The derivatization proceeded quantitatively within 1 h at room temperature. The corresponding diastereomers were well resolved an ODS column with acetonitrile-acetate buffers a mobile phase and monitored at UV 254nm. (omitted)

• Journal of the Korean Chemical Society
• /
• v.43 no.1
• /
• pp.7-119
• /
• 1999

• Proceedings of the Korea Society of Environmental Biology Conference
• /
• 2004.05a
• /
• pp.41-41
• /
• 2004

• Journal of Plant Biology
• /
• v.36 no.3
• /
• pp.297-300
• /
• 1993

Six flavonoid compounds from the ethyl acetate fraction of Machilus thunbergii leaves were identified by HPLC. Separation by reversed phase chromatography on u-Bondapak C18 column was achieved by isocratic elution. The contents of the major flavonoids, guaijaverin and quercitrin were about 0.48% (w/w) and 0.98% (w/w) for the methanol extract, respectively.

• Analytical Science and Technology
• /
• v.7 no.1
• /
• pp.103-114
• /
• 1994

The elution behaviors of Ni(II), Cu(II), Co(II), and Cr(II) in 1-phenyl-3-methyl-4(2-hydroxy-5-X-phenylazo)-5-pyrazolone, [Pm(2-OH)(5-X)PaPz](X=H, $CH_3$, $NO_2$, Cl) chelates have been studied by reversed phase HPLC. Thirteen metal-[Pm(2-OH)(5-X)PaPz] chelates were prepared and characterized by UV, IR, MS, and ICP spectroscopic methods. These metal-2-hydroxyarylazopyrazolone chelates were successfully separated on Novapak-$C_{18}$ column using methanol/water mixtures as a mobile phases. It was found that the chelates were eluted properly in an acceptable range of the capacity factor value($0{\leq}log\;k^{\prime}{\leq}1$). The dependence of the capacity factor(log k') on the volume fraction of water in the binary mobile phase showed a good linearity. Also, there was a good linear dependence of the capacity factor on the liquid-liquid extraction distribution ratio($D_c$) in methanol-water/n-pentadecane extraction system by the batch method. It suggested that the retention of the chelates in the reverse phase liquid chromatographic system be largely due to the solvophobic effect.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.23 no.6
• /
• pp.546-552
• /
• 2013

A cantilevered piezoelectric energy harvester(PEH) and an auxiliary mass-spring unit can be integrated into a novel two-degrees-of-freedom PEH where its lowest eigenmode is not an in-phase modes but an out-of-phase mode. This typical behavior was shown to enhance output power considerably compared with its stand-alone counterpart. The objective of this study is to newly develop a continuum-based mathematical model suitable for efficient analysis of the mode-sequence reversed PEH. Once such a mathematical model is available, various physical behaviors can be analytically investigated for better designs. After a new mathematical model is developed, its validity is checked by using ANSYS results, in terms of resonant frequency, open-circuit voltage, and output power with a specified external resistance.

• Analytical Science and Technology
• /
• v.6 no.4
• /
• pp.383-390
• /
• 1993

Retention behaviors of aliphatic and aromatic compounds were investigated with Van der Waals volume which represented the molecular size. The organic solvents, methanol, acetonitrile and tetrahydrofuran, were mixed with water at various ratio, respectively. The selectivity of organic solvents were tested by change of column temperature. The capacity factor was increased linearly according to the enlargement of molecular size. Therefore, Van der Waals volume was useful to predict the elution of organic molecules in reversed-phase column. The order of elution capacity of solvents was methanol

• Applied Biological Chemistry
• /
• v.41 no.6
• /
• pp.410-413
• /
• 1998

The major protein (GMP) from the roots of Panax ginseng C. A. Meyer was purified, using gel filtration and ion exchange chromatography followed by reversed-phase and ion exchange FPLC. Staining analysis indicated that the protein has a carbohydrate moiety, which was also shown by band shift experiments using various glycosidases. Electrophoretic and gel permeation studies showed that GMP has an apparent molecular weight of 63 kDa composed of possibly two subunits of 25 kDa containing carbohydrate moiety. GMP showed an anticomplementary activity on the hemolysis of red blood cells, which is a screening tool for inflammation mediator search.

• Analytical Science and Technology
• /
• v.15 no.3
• /
• pp.190-195
• /
• 2002

We analysed mutation of ${\beta}_2$-adrenergic receptor gene that controls bronchial asthma by denaturing high performance liquid chromatography (DHPLC) according to ion-pair reversed-phase high performance liquid chromatography (IP-RP-HPLC). We extracted genomic DNA from 50 asthma patients, amplified DNA using PCR, and analysed PCR product by DHPLC. As a result, we obtained that mutation frequency was 15 (30%) among 50 cases. Consequently DHPLC mutation detection was confirmed that the result of direct sequencing was coincide exactly.

• Journal of Pharmaceutical Investigation
• /
• v.25 no.3
• /
• pp.239-247
• /
• 1995

The physico-chemical stability of aucubin, a hepatoprotective iridoid glucoside, in buffered aqueous solutions was studied using a stability-indicating reversed-phase high performance liquid chromatography. The degradation of aucubin followed the pseudo-first-order kinetics. In strong acidic regions, aucubin was rapidly degraded by the specific acid catalysis, forming dark brown precipitates. From the rate-pH profiles, it was found that aucubin was most stable at the pH of about 10. From the temperature dependence of degradation, activation energies for aucubin at pH 2.1 and 4.9 were calculated to be 22.0 and 24.3 kcal/mole, respectively. The shelf-life $(t_{90%})$ for aucubin at pH 9.07 and $20^{\circ}C$ was predicted to be about 603 days. A higher ionic strength accelerated the degradation of aucubin at pH 4.01. The effect of metal ions on the degradation rate of aucubin at pH 7.16 was in the rank order of $Cu^{2+}\;>\;Fe^{3+}\;>\;Co^{2+}\;>\;Fe^{2+}\;>\;Mg^{2+}$. On the other hand, $Mn^{2+}\;and\;Ba^{2+}$ slowed the degradation rate.