• Applied Biological Chemistry
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• v.23 no.1
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• pp.14-22
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• 1980

White and black sesame produced in Korea were defatted with ethyl ether or n-hexane. Defatted sesame meal was extracted with water and salt solution, and protein extraction was precipitated at various pH 1 through 12, with trichloro acetic acid (TCA), tannic acid and ammonium sulfate, respectively. Protein was purified by Sephadex A-25, G-75, G-100 and G-200, and identified its protein fraction by polyacrylamide gel electrophoresis. Amino acids composition of protein in white sesame was analyzed by automatic amino acid analyzer. Protein contents of white sesame, black sesame and sesame meal are 20.5%, 19.2%, and 44.7%, respectively. n-Hexane was the most suitable solvent for extraction of oil from sesame. Crude protein precipitation was better in higher pH. The protein extraction was more effective with the solution containing sodium chloride tinder the pH 8. Globulin in total protein was high and prolamin was less than in other cereal proteins. Glutamic acid contents of white sesame and sesame globulin were 17.1%, and 20%, respectively. Both proteins contained relatively high levels of essential amino acids. 12-13 bands were found in water soluble protein and 2 bands in salt soluble protein were detected by the disc gel electrophoresis, and were identified in both of white and black sesame. The salt soluble protein of white sesame could be purified by Sephadee G-100 and G-200.

• Journal of Korea Soil Environment Society
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• v.2 no.2
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• pp.73-79
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• 1997

Removal of the Arsenic components from the closed mine tailings has been attempted by the alkali-leaching method. Two tailings collected from the Daduck and Yuchon mine which were already closed many years ago were leached with caustic soda solutions. The Arsenic components in the leach liquor resulted from the alkali treatment of tailings could be removed fairly well in the form of insoluble calcium-Arsenic compound by the precipitation with calcium chloride. As a result, the extraction of about 60~90% Arsenic from the tailings could be obtained depending on the leaching conditions and the influence of temperature and the slurry density on the extraction of Arsenic was also found to be very small at the NaOH concentration more than 0.5N. In addition, it seemed that a caustic soda solution over 0.5N NaOH could be used repeatedly for the leaching of tailings since the consumption of NaOH was not so great in a leaching of them. As far as the precipitation of Arsenic components was concerned, more than 99% of Arsenic could be precipitated within 10 minutes by the addition of 2wt% CaC12 in to the leach liquor.

• Applied Chemistry for Engineering
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• v.7 no.4
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• pp.802-808
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• 1996

Silicic acid(SA) was extracted with organic solvents from aqueous sodium silicate solutions acidified with dilute sulfuric acid. Tetrahydrofuran(THF), isopropyl alcohol and acetone were used as organic solvents. The extraction degree of Si and the removal efficiency of Na is determined according to kinds of solvent and the mixing ratios of solvent, sodium chloride and $H_2O$. Optimum conditions for the preparation of high purity SA were THF as an organic solvent, volume ratio of organic solvent/SA : 1 (organic solvent 10ml/10ml SA) and the amount of NaCl addition 2.5g/10ml SA. The extraction degree of Si and the removal efficiency of Na at that point were 86.2% and 99.95% respectively and the purity of SA was 99.96%.

• KSBB Journal
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• v.16 no.2
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• pp.174-178
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• 2001

Soybeans contain the phytoestrogens genistein and daidzein, their glucosides genistin and daidzin and coumesterol. These isoflavonoid compounds are capable of producing an estrogenic response in a number of diverse species. This study determined optimum conditions for the extraction of the main isoflavones(daidzin, genistin, daidzein, genistein) in defatted soybean meal using high-performance liquid chromatography. The best optimum extraction was achieved at 75% ethanol, $80^{circ}C$, pH4 and a three hour contact time. In addition, isoflavones with high purity were separated by adding up to 4%(w/v) of calcium chloride dihydrate. Most soybean extracts were composed of $beta$-glucosidic conjugate(daidzin, genistin) which is difficult to adsorb in body. Therefore, $beta$-glucosidase was used to convert as conjugate to aglycone form (daidzein, genistein) which is easy to adsorb. The optimal conditions of enzyme reaction involved to be 8.4 units of enzyme concentration, pH5.0, $40^{circ}C$ and 40 minutes.

• Analytical Science and Technology
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• v.25 no.3
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• pp.178-189
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• 2012

As phthalates classified as toxic to reproduction category 2 and endocrine disrupting chemicals were more strictly regulated as Substances of Very High Concern (SVHC) for authorization in under EU REACH and considered as priority substances in RoHS II, standardization of phthalate testing method is now being proposed in IEC 62321 of IEC TC 111 and the 2nd revision of KS M 1991 is also finished. In order to assist standardization activities related to phthalating testing, solvent extraction part of existing national standards were compared and verified. Recovery of DEHP (diethylhexyl phthalate) from PVC (polyvinyl chloride) by Soxhlet extraction increased in the order of methanol, toluene, dichloromethane and hexane from 46.9% to 95.3% as measured by GC-MS. Optimum extraction time was verified to be 6 hours using hexane. Recovery of DBP (dibutyl phthalate), BBP (butylbenzyl phthalate), and DEHP from different matrixes such as PVC, nitro cellulose, ABS (acrylonitrile butadiene styrene). and EPDM(ethylene propylene diene monomer) rubber were evaluated to be more than 90% up to 99%. The detection limits of phthalates in solvent extraction followed by GC-MS analysis were 0.08~0.3 ${\mu}g/mL$ in solution and 8~30 mg/Kg in polymeric samples. GC-MS analyses of phthalates were carried out using different solvent extraction based on the EN 14372, ASTM D 7083, Japanese test method (MHLW 0906-4) and KS M 1991, proving that equivalent recoveries ranging from 98%~99% were obtained. DBP and DEHP were detected in three consumer products such as a child toy, a power cable and manicure with the amount of 22~1,910 mg/kg.

• Analytical Science and Technology
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• v.36 no.6
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• pp.291-299
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• 2023

The benzo[a]pyrene in edible oils is extracted using methods such as Liquid-liquid, soxhlet and ultrasound-assisted extraction. However these extraction methods have significant drawbacks, such as long extraction time and large amount of solvent usage. To overcome these drawbacks, this study attempted to improve the current complex benzo[a]pyrene analysis method by applying the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method that can be analyzed in a simple and short time. The QuEChERS method applied in this study includes extraction of benzo[a]pyrene into n-hexane saturated acetonitrile and n-hexane. After extraction and distribution using magnesium sulfate and sodium chloride, benzo[a]pyrene is analyzed by liquid chromatography with fluorescence detector (LC/FLR). As a result of method validation of the new method, the limit of detection (LOD) and quantification (LOQ) were 0.02 ㎍/kg and 0.05 ㎍/kg, respectively. The calibration curves were constructed using five levels (0.1~10 ㎍/kg) and coefficient (R²) was above 0.99. Mean recovery ratio was ranged from 74.5 to 79.3 % with a relative standard deviation (RSD) between 0.52 to 1.58 %. The accuracy and precision were 72.6~79.4 % and 0.14~7.20 %, respectively. All results satisfied the criteria ranges requested in the Food Safety Evaluation Department guidelines (2016) and AOAC official method of analysis (2023). Therefore, the analysis method presented in this study was a relatively simple pretreatment method compared to the existing analysis method, which reduced the analysis time and solvent use to 92 % and 96 %, respectively.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.1
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• pp.23-40
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• 1999

The analysis of thiodiglycolic acid in urine has been used as an index of biological exposure to vinyl chloride. Unfortunately thiodiglycolic acid has a strong hydrophilic character, because it has two carboxylic groups, so that it can only be extracted with organic solvent with a great difficulty. Underivatized thiodiglycolic acid tends to tail because of non-specific interaction with the inert support. Therefore, esterification is the obvious first choice for derivatization of thiodiglycolic acid, particularly for gas chromatography. In this study, the focus of interest is to compare two method of esterifications (methylation and silylation). Methylation is to make the methyl ester of thiodiglycolic acid by reaction with diazomethane. Silylation is to make the trimethylsilyl ester of thiodiglycolic acid by reaction with N-trimethylsily-ldiethylamine. The results and conclusions are as the following: 1. The detection limit (sensitivity) of methylated thiodiglycolic acid was $5.00{\mu}g/m{\ell}$ and silylated thiodiglycolic acid was $3.07{\mu}g/m{\ell}$ by gas chromatography with flame ionization detector. 2. The optimal liquid-liquid extraction of thiodiglycolic acid was as following: To each of the tubes, $15m{\ell}$ of urine, concentrated sulfuric acid (pH 1 - 2) and 5 gsodium sulfate were added. The samples was extracted three times with $5m{\ell}$ ethylacetate each time. 3. The methylated thiodiglycolic acid was more stable than silylated thiodiglycolic acid in extractional solvent which contained humidity. 4. The precision (pooled coefficient of variation for 4 days) of the analysis was 0.07324 in methylated thiodiglycolic acid with external standard calibration, and 0.07033 in methylated thiodiglycolic acid with internal standard calibration. 5. The precision (pooled coefficient of variation for 4 days) of the analysis was 0.10914 in silylated thiodiglycolic acid with external standard calibration, and 0.13602 in silylated thiodiglycolic acid with internal standard calibration. From the above results, the analysis of methylated thiodiglycolic acid was more sensitive (limit of detection) than silylated thiodiglycolic acid by gas chromatography. However, the methylated thiodiglycolic acid was stable in the humidity and was separated sharply on chromatogram. Also, analysis of methylated thiodiglycolic acid was more precise (pooled coefficient of variation for 4 days) than silylated thiodiglycolic acid. In conclusion, it is established that the analysis of methylated thiodiglycolic acid is appropriate for biological monitoring of exposure to vinyl chloride.

• The Korean Journal of Food And Nutrition
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• v.31 no.6
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• pp.775-782
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• 2018

The purpose of this study was to investigate effects of Crataegus pinnatifida var. psilosa extracts obtained from 95% methanol and water. Methylene chloride, ethyl acetate, and methanol were used to fractionate the 95% methanol extract and each fraction was testified total polyphenol contents, electron donating abilities, the scavenging abilities of superoxide anion radical, as well as hydrogen peroxide. Extraction yields of 95% methanol and water from Crataegus pinnatifida var. psilosa were 25.40%, 23.12% respectively. Total polyphenol contents were $28,708.0{\pm}1,755.05{\mu}g\;GAE/mL$ in 95% methanol, revealing the highest among them, $12,726.67{\pm}479.33{\mu}g\;GAE/mL$ in water extract, $15,854.67{\pm}498.38{\mu}g\;GAE/mL$ in methanol fraction, $11,810.67{\pm}584.48{\mu}g\;GAE/mL$ in ethyl acetate fraction, and $5294.67{\pm}190.36{\mu}g\;GAE/mL$ in methylene chloride fraction. Total polyphenol contents revealed significant differences (p<0.05) between the solvents. In the experiment of the electron donating ability, water extract revealed $84.33{\pm}0.1%$ scavenging ability, the highest. Other extracts and fractions were $81.8{\pm}1.11%$ for water, $79.73{\pm}1.32%$ for ethyl acetate fraction, $75.73{\pm}2.17%$ for methylene chloride fraction, and $42.1{\pm}5.01%$ for methanol fraction, the lowest electron donating ability. Electron donating abilities revealed significant difference (p<0.05) between the solvents. In the experiment of superoxide anion radical scavenging ability, ethyl acetate fraction($0.0026{\pm}0.0002$) had the highest scavenging ability, and the others revealed slight increase rather than decrease in scavenging ability. Hydrogen peroxide scavenging ability revealed the highest in methanol fraction ($-0.00206{\pm}0.00165$) and the others were as follow; water extract ($0.00157{\pm}0.00249$), 95.0% methanol extract ($0.005{\pm}0.0036$), methylene chloride fraction ($0.0039{\pm}0.00364$), and ethyl acetate fraction ($0.0002{\pm}0.00059$).

• Archives of Pharmacal Research
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• v.9 no.3
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• pp.131-138
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• 1986

A specific and sensitive gas chromatographic (GC) procedure with the flame photometric detector (FPD) was developed for determination of barbiturates such as barbital, allobarbital, secobarbital, phenobarbital and thiopental in plasma. In order to evaluate the performance of the FPD, the results were campared with those of the flame ionization detector (FID). After extraction of barbiturates from plasma, the barbiturates were quantitatively N, N-dimethylthiometyl (MTM)-derivatized with methylthiomethyl chloride in 1, 8-diazabicyclo [5, 4, 0] undec-7-ene catalyst. The data indicate that the FPD is about 4 times more sensitive than the FID for barbiturates, although it is less reproducible. The FPD also produced chromatogram with less back ground for extracted plasma sample. The FPD also produced chromatogram with less background for extracted plasma sample. The minimum detectable amount of MTM-thiopental on 3% OV-225 column was 4, 4fmol and that of other MTM-barbiturate was about 10.0fmol.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.350-353
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• 2004

This study was conducted for a rapid and simple method using GC/FID and SPME to dectermin gasonline and chlorinated solvents simultaneity. A sodium chloride concentration of 25%(vol/w) combined with such as magnetic stirried, an absorption time of 20min, an extraction temperature of 4$0^{\circ}C$, the volume of minimized 50mL of gaseous phase and a desorption time of 5min pleprovided the greatest sensitivity while maintaining analytical efficiency. Analytical parameter such as linearity was also evaluated. The linear range extend from 30 to 500ppb. The results of chlorinated solvents and gasoline mixed samples showed that solvents have been completely removed from the sample preparation step and more accurated than those obtained by the other methods.