• The Korean Journal of Zoology
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• v.34 no.2
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• pp.196-202
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• 1991

Juvenile honnone binding protein (JHBP) was identified in the last instar larval hemolymph of Lymantria dispar using dextran coated charcoal (DCC) binding assay and gel filtration. The p1 value of JHBP was estimated to be 5.3. JHBP was partially pudfied by polyethylene glycol(PEG) precipitation, DEAE-cellulose ion-exchange chromatography and gel filtration, and was confirmed by DCC binding assay.

• Applied Biological Chemistry
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• v.28 no.2
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• pp.82-87
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• 1985

Aiming at the improvement of accuracy and sensitivity of gibberellin analysis by gas chromatography-selected ion monitoring (GC-SIM), the mass spectra of two types of 29 gibberellin derivatives, methyl ester-trimethylsilyl ethers and trimethylsilyl ester-trimethylsilyl ethers, were obtained and their advantages and disadvantages in GC-SIM analysis are discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.695-698
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• 2000

This paper present the result of the investigation, the distribution of salt contamination with the influence of geographical condition. To get the ESDD data, a conventional brush washing method was adapted, and IC(ion chromatography) was used to measure the quantity of anions, such as Cl$\^$-/ and SO$_4$$\^$2-/. And we make an analysis on the distribution of salt contamination with the increase of distance from shore. With 10 month ESDD data, we seek the 95% ESDD value with interpolation method. With these analyses, we had obtained the formulation concerned with the distance from sea. And could know the composition of contamination.

• Bulletin of the Korean Chemical Society
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• v.15 no.9
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• pp.786-791
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• 1994

A simple and rapid sample pretreatment process necessary for determination of metal oxides in water was proposed. Samples were injected into the continuous-flow tube installed inside the microwave oven and the treated samples were cooled before entered to the Ion Chromatography (IC) or Inductively Coupled Plasma (ICP). By coupling this microwave digestion system with IC or ICP, a fully automatic analytical procedures may be easily established. In this study, two different types of digestion methods were considered; the open tubing method (OTM) and the restraint tubing method (RTM). The RTM was proved to be 3 times faster in digestion period and 10 times higher in detection range than the OTM. Validation of proposed sample digestion system was carried out by using an ICP. The results showed that both of continuous-flow methods, the OTM and the RTM were comparable in accuracies with the conventional batch-type vessel digestion method.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.329-332
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• 1999

An automated method is developed for simultaneous determination of water soluble gases at parts per trillion level in the environmental air. The method involves temperature-humidity control of sample air using a thermostated humidifier, collection of analyte gases by condenser-type effluent diffusion denuder and subsequent effluent analysis by ion chromatography. The detection limits (3(σ) of the method for CH3COOH, HNO2 and SO2 gases are 0.022, 0.019 and 0.009 ppbv, respectively. The precisions range from 0.3 to 3.0% RSD. The method has been successfully applied to urban air analysis and some results for nitrous acid and SOx, in Seoul air are presented.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.3
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• pp.236-241
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• 2005

A decolorization process using ion exchange chromatography was developed to refine rhEGF as a cosmetic ingredient. A macroreticular resin (D314) was selected, with respect to its high decolorization rate and recovery yield of rhEGF, and the operational conditions of the decolorization process optimized. The optimum conditions were as follows: the rhEGF effluent was ion exchanged at a flow rate of 60.0mL/h, with an effluent pH 5.0, using a chromatographic column (i.d. 16mm) packed with D314, with a 7.5cm in bed height. The decolorization process was carried out under the optimum conditions, and halted when the effluent volume reached 350mL, giving a decolorization rate and recovery yield of rhEGF higher than 67 and $80\%$, respectively. When the decolorization rate exceeded $67\%$, the final product turned out to be white or light yellowish, which was to the satisfaction of the cosmetic standard.

• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1221-1227
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• 2011

Ethyl pyruvate (EP) is known as a scavenger of reactive oxygen species (ROS) in the body through its role in the donation of diketone groups to metals to form an EP-metal complex. In order to develop a method for the quantification of EP in biological media, a sensitive and specific, high-performance liquid chromatographyelectrospray ionization-mass spectrometry (HPLC-ESI/MS) method is used to determine the EP-alkali metal ion binding species. The analyte was separated on a ZORBOX SB-C8 ($3.5{\mu}m$, $30mm{\times}2.1mm$ I.D.) column and analyzed in selected ion monitoring (SIM) mode with a positive ESI interface using the m/z 255 $[2M + Na]^+$ ion. The method was validated over the concentration range of $0.5-60.0\;{\mu}g$/mL under 1/9 (v/v) of acetonitrile/methanol solvent system with flow rate 0.05 mL/min. The limit of quantification (LOQ) was $0.5{\mu}g$/mL.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.6
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• pp.589-598
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• 1998

This study was conducted to investigate the chemical characteristics of Precipitation at Seoul, Yangpyong, Hongchon and Inje in the central part of Korean peninsula during the period from March 1994 to November 1997. The precipitation samples were collected by automatic wet-only sampler. The samples were analyzed for major anions (SO42-, NO3-, Cl-, F-) and cations(NH4+, Ca2+, Mg+, Na+, K+), in addition to acidity and electrical conductivity. The analytical instrument for water soluble ionic components was ion chromatography. The volume - weighted mean PH were 4.73, 4.87, 4.89 and 4.81 at Seoul, Yangpyong, Hongchon and Inje, respectively. The sums of cation concentrations was slightly greater than the sums of anion concentrations. Also, the highest ion component was SO42- in anions and NH4+ in cations. The mean equivalent ratios of SO42- to NO3- were found by 2.96, 2.71, 2.43 and 2.25 at Seoul, Yangpyong, Hongchon and Inje, respectively. The factor analysis was conducted in order to make the large and diverse data set as manageable levels and to qualitatively examine the relationship between the variables. It showed that major sources of pollutants in precipitation were from the anthropogenic in Seoul, the natural in Hongchon, and the anthropogenic and natural in Yangpyong and Inje.

• BMB Reports
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• v.35 no.2
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• pp.228-235
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• 2002

Methionine aminopeptidase (MetAP) catalyzes the removal of an amino-terminal methionine from a newly synthesized polypeptide. The enzyme was purified to homogeneity from Bacillus stearothermophilus (KCTC 1752) by a procedure that involves heat precipitation and four sequential chromatographs (including DEAE-Sepharose ion exchange, hydroxylapatite, Ultrogel AcA 54 gel filtration, and Reactive red 120 dye affinity chromatography). The apparent molecular masses of the enzyme were 81,300 Da and 41,000 Da, as determined by gel filtration chromatography and sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE), respectively. This indicates that the enzyme is comprised of two identical subunits. The MetAP specifically hydrolyzed the N-terminal residue of Met-Ala-Ser that was used as a substrate, and exhibited a strong preference for Met-Ala-Ser over Leu-Gly-Gly, Leu-Ser-Phe, and Leu-Leu-Tyr. The enzyme has an optimal pH at 8.0, an optimal temperature at $80^{\circ}C$, and pI at 4.1. The enzyme was heat-stable, as its activity remained unaltered when incubated at $80^{\circ}C$ for 45 min. The Km and Vmax values of the enzyme were 3.0mM and 1.7 mmol/min/mg, respectively. The B. stearothernmophilus MetAP was completely inactivated by EDTA and required $Co^{2+}$ ion(s) for activation, suggesting the metal dependence of this enzyme.

• FOCUS: LIFE SCIENCE
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• no.1
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• pp.5.1-5.3
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• 2024

The document discusses the regeneration of Partisil/Partisphere ion-exchange columns in chromatography. It mentions that column efficiency can diminish with use due to the accumulation of sample and/or mobile phase impurities at the head of the column. This can lead to a change in back pressure, lower column efficiency, and sometimes a change in selectivity. The document outlines a procedure that may restore column performance. The document also provides everyday practices to enhance the lifetime of a column. These include using only high-purity HPLC solvents and buffers, using freshly prepared mobile phases and buffers, filtering mobile phases to remove particulates, using appropriate sample clean-up procedures, using a guard column or pre-column filter, and working within the pressure and flow rate limitations of the column. For the regeneration of Partisil/Partisphere SAX, SCX, WAX, and WCX columns, the document suggests passing 20 column volumes of various mobile phases through the column. These include a buffer wash, distilled water, an acid wash, a chelating wash, a methanol wash, and a buffer for separation. The document emphasizes that not all of these wash steps are required for every column clean-up and that some chromatographers require only a combination of certain steps.