• Corrosion Science and Technology
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• v.5 no.6
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• pp.201-205
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• 2006

HYPER(Hybrid Power Extraction Reactor) is the accelerator driven subcritical transmutation system developed by KAERI(Korea Atomic Research Institute). HYPER is designed to transmute long-lived transuranic actinides and fission products such as Tc-99 and I-129. Liquid lead-bismuth eutectic (LBE). Has been a primary candidate for coolant and spallation neutron target due to its appropriate thermal-physical and chemical properties, However, it is very corrosive to the common steels used in nuclear installations at high temperature. This corrosion problem is one of the main factors considered to set the upper limits of temperature and velocity of HYPER system. In this study, a parametric study for a corrosion model was performed. And a preliminary corrosion model was also developed to predict the corrosion rate in isothermal Pb and LBE flow loops.

• YAKHAK HOEJI
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• v.32 no.1
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• pp.6-13
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• 1988

A gas chromatographic method is described for the determination of volatile free acids(VFAs) in body fluids. VFAs were trace enriched from body fluids by liquid-solid extraction using Chromosorb P as the solid sorbent and ether as the eluant. The enriched VFAs were injected in splitless injection mode onto a HP-20M fused silica capillary column. The flame ionization detector was used as the detector. The present method was applied to the profiling of VFAs in body fluids from patients suffering from the infectious disease, hepatitis. The VFAs concentrations were high in saliva of hepatitis patients and isobutyric acid detected in sera of hepatitis patients compared to healthy subjects.

• YAKHAK HOEJI
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• v.46 no.4
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• pp.231-236
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• 2002

A high-performance liquid chromatographic method for the simultaneous quantitative analysis of methylparaben (MP), ethylparaben (EP), propylparaben (PP), butylparaben (BP) and imidazolidinyl urea(IU) or diazolidinyl urea(DU) in cosmetics was studied by using a cyano-propyl column and 0.05M hexanesulfonic acid at 228 nm. Calibration curves were found to be linear in the 60-1000 $\mu\textrm{g}$/mL range (parabens), 100-1,250 $\mu\textrm{g}$/mL range (IU) and the 120-2000 $\mu\textrm{g}$/mL range (DU). Linear regression analysis of the data demonstrates the efficacy of the method in terms of precision and accuracy. An extraction method is developed and validated in order to apply this chromatographic method to a commercial cosmetic cream. The precision of this method, calculated as the relative standard deviation (RSD) of the recoveries (0.46-2.71％) was excellent for all compounds.

• Archives of Pharmacal Research
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• v.23 no.5
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• pp.441-445
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• 2000

Achiral-chiral column switching HPLC assay was developed to allow the separation and quantification of the enantiomers of terbutaline in human plasma by means of fluorescence detection. Plasma samples were prepared by solid-phase extraction with sep-pak silica, followed by HPLC assay. The enantiomers of terbutaline and the internal standard were separated from the biological matrix on a silica column, and the two enantiomers were resolved and quantified on a Sumichiral OA-4900 column. The two columns were connected by a switching valve equipped with silica trap column, The trap column was used to concentrate the terbutaline in the eluent from the achiral column before back flushing onto the chiral phase. For each enantiomers, the assay was linear between 2.5-125 ng/$m\ell$ (r=0.9999) and detection limit was 1.0 ng/$m\ell$ .

• Journal of Microbiology and Biotechnology
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• v.25 no.8
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• pp.1257-1264
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• 2015

Trichoderma strain T-33 has been demonstrated to have inhibitory effect on the fungus species Cytospora chrysosperma. Here, an active antifungal compound was obtained from Trichoderma strain T-33 extract via combined separation technologies, including organic solvent extraction, liquid chromatography, and thin-layer chromatography. The purified compound was further characterized by advanced analytical technologies to elucidate its chemical structure. Results indicated that the active antifungal compound in Trichoderma strain T-33 extract is 2,5-cyclohexadiene-1,4-dione-2,6-bis (1,1-dimethylethyl).

• Journal of the Korean Society of Tobacco Science
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• v.32 no.2
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• pp.70-76
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• 2010

A simple and sensitive automatic amino acid analyzer method for the determination of free amino acids in tobacco was described. Sample preparation consisted of a single step of extraction with 0.1 mol HCl at ambient temperature in 60 min by sonication, followed by filtration of an aliquot. Automated amino acid analyzer was used to construct a post-column ninhydrin reaction unit to monitor amino acids separated by liquid chromatography using a series of eluting buffers. By optimization of sample preparation, separation of 19 amino acids was achieved. Limits of quantitation was 0.01 mg/g, coefficients of variation ranged from 0.5 % to 8.9 % and recoveries range from 85 % to 106 %. The method was applied to the analysis of amino acids contents of tobacco leaves in different varieties.

• Bulletin of the Korean Chemical Society
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• v.22 no.9
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• pp.958-962
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• 2001

The chiral amine auxiliary mediated stereoselective alkylation reactions of glycinamides 1-6 and 15-17 using phase transfer catalyst (PTC) for liquid-solid extraction are described. The secondary N-(diphenylmethylene) glycinamides 1, 2 and 3 give better selectivities and yields than tertiary N-(diphenylmethylene) glycinamides 4, 5 and 6. Alkylation of the glycinamide 1 and 2 using 18-Crown-6 as a PTC in toluene at $-40^{\circ}C$ gives best selectivities and yields. Alkylations of N-(4-chlorophenylmethylene)glycinamides 15, 16 and 17 under same PTC conditions give $\alpha$, $\alpha-disubstituted$ amino acid derivatives 18, 19 and 20 with low diastereoselectivities.

• Proceedings of the Ginseng society Conference
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• 2002.10a
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• pp.486-490
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• 2002

In different approaches ginsenosides were extracted from Korean ginseng roots by ammonia and for comparison with methanol-water and water. The extracts have been analyzed qualitatively and quantitatively to evaluate yield and selectivity of extractions of ginsenosides. Water supplied the lowest yield. The yields of extracts with liquid ammonia were higher than those with methanol-water. However, this is partly due to the conversion of malonyl ginsenoside to normal ginsenosides by ammonia. It was proved by HPLC that malonyl-ginsenosides $m-Rb_1,\;m-Rb_2,$ m-Rc and m-Rd were converted to the corresponding neutral ginsenosides. Furthermore, ginsenosides from ginseng roots were extracted by alkaline methanol-water $(60\%)$ solutions. Alternatively, the extracts of the methanol-water $(60\%)$ extraction were treated with sodium hydroxide solution. Both methods also convert the malonyl-ginsenosides to neutral ginsenosides.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.223.1-223.1
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• 2003

D-Amygdalin and its conversion product, neoamygdalin, were clearly separated on reverse-phase column chromatography by an optimized eluent of 10 mM sodium phosphate buffer (pH 3.5) containing 8.5% acetonitrile. Linearity for analyzing D-amygdalin and neoamygdalin was observed in the range from 0.05 to 0.5 mM. The detection limits for D-amygdalin and neoamygdalin were ca. 5 uM per injected amount. When extracting amygdalin from a whole piece of Armeniacae Semen in the boiling aqueous solution, there was almost no influence of emulsin; it resulted in higher extraction yield. (omitted)

• Journal of Applied Biological Chemistry
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• v.64 no.1
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• pp.13-17
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• 2021

Qantitative analysis of six compounds: (+)-catechin, benzoic acid, gallic acid methyl ester, paeonol, paeoniflorin, and albiflorin from Paeonia lactiflora extracts was performed using high-performance liquid chromatography and an ultraviolet (UV) detector, following different extraction methods. A reverse-phase column was used in a gradient elution system, and UV detection was performed at 280 nm. The results showed that the quantity of paeoniflorin was the highest in ethanol and water extracts (73.89 and 57.87 mg/g, respectively) among the six compounds. This study contributes a good analysis method for the contents of P. lactiflora and would be propitious for developing medicines and functional foods.