• Analytical Science and Technology
• /
• v.15 no.1
• /
• pp.72-79
• /
• 2002

Di-(2-ethylhexyl)phthalate (DEHP) may be released from plasticized poly(vinyl chloride) (PVC) articles. In the cases of various methods for the quantitative analysis of migrating DEHP, there are much differences in migrating quantity according to the experimental methods. It is therefore important to make the comparison and analysis between these two results. A study of DEHP migration from blood and infusion bags has been carried out in different methods to evaluate the amount of DEHP migration using gas chromatograph and UV-vis spectrophotometry. Five PVC bags were cut into plane sheets in size of $40{\times}10{\times}0.4mm$, then were immersed in extraction solvent for an hour to release DEHP. It was determined by a gas chromatograph that $23.2{\sim}70.9{\mu}g/mL$ of DEHP was extracted. While extraction solvent was injected into PVC bags which were then placed for an hour to leach DEHP out. It was checked by a UV-vis spectrophotometer that the concentration of DEHP in extraction solvent was $24.8{\sim}41.3{\mu}g/mL$. Two results show different values according to the extraction conditions and experimental methods and the gas chromatographic results were converted into UV-vis spectroscopic results on condition that DEHP would be extracted equally per unit time and unit contact area. It was concluded that DEHP migrating amounts are approximately equal in two analytical methods.

• Korean Journal of Environmental Agriculture
• /
• v.1 no.1
• /
• pp.14-21
• /
• 1982

Analytical methods for residues of six N-methylcarbamate insecticides were investigated to compare the minimum detectability, recovery from several crops and feasibility of multiple residue analysis. Those methods studied in this work included spectrophotometry by diazotization and gas chromatography by N-trifluoroacetylation(TFA), pentafluorobenzylether(PFB) and dinitrophenylether (DNP) derivatization. Maximum absorbed wavelength of the diazotized MIPC, XMC, BPMC, propoxur and carbofu ran was around 460 ㎚, while that of carbaryl recorded 510 ㎚. Recovery from brown rice and apple by diazotization method ranged from 80 to 120% and minimum detectable limits were 0.03 to 0.05 ppm in 50 g of the sample. Minimum detectability of PFB derivatives by gas chromatography was superior to TFA and DNP derivatives. DNP derivatives showed the longest retention time among the given derivatives. Recovery from crops by gas chromatographic met hod ranged 74 to 94%, 78 to 93%, and 85 to 99% in brown rice, rice straw and apple, respectively. Limit of detection was 0.01 ppm for TFA, 0.005 ppm for PFB and 0.02 ppm for DNP derivatives in 50 g of the crop samples.

• Korean Journal of Food Science and Technology
• /
• v.31 no.2
• /
• pp.285-292
• /
• 1999

An analytical method applicable to quality control and its optimum conditions were studied for rapid and efficient analysis of sorbic and benzoic acids used as preservatives in the commercial soybean paste. In gas chromatographic analysis of sorbic and benzoic acids, the application of HP-FFAP (acid modified polyethylene) wide bore column improved the separation ability significantly. By setting the oven temperature of GC to $200^{\circ}C$, the total elapsed time for quantitative analysis was also reduced to the level required in using packed column. By extracting sorbic and benzoic acids from soybean paste with an automatic steam distillation device, the elapsed time for analysis was reduced by 80% more compared to using conventional steam distillation method. The recoveries of sorbic and benzoic acids by the automatic steam distillation were 98.1% and 99.9%, respectively. The sorbic acid was found in 3 samples of 14 commercial soybean pastes, of which contents were $466{\sim}530ppm$, while $0.3{\sim}4.4ppm$ of benzoic acid was found in all the samples.

• Korean Journal of Environmental Agriculture
• /
• v.27 no.3
• /
• pp.279-284
• /
• 2008

We investigated whether carboxylate exudation of Brassica pekinensis Rupr. was affected by nitrate deposition from simulated acid rain. A gas chromatographic (GC) analysis was employed for the determination of low molecular weight organic acids (LOA) in rhizosphere soils, bulk soil, roots and leaves of Brassica pekinensis Rupr.. Rhizosphere soils were collected after 8 weeks of plant growth by first removing the bulk soil from the root system and then by mechanical move off the rhizosphere soil that adhered to the root surface with soft brush. Soil and plant materials were simultaneously extracted with the mixture of methanol and sulfuric acid (100:7, v/v). Seven organic acids, oxalic, malonic, fumaric, succinic, maleic, L-malic and citric acid were identified and quantified by GC equipped with FID. Oxalic, L-malic, and citric acids were found in both the bulk and rhizosphere soils, while most LOAs were not detected in the control treatment. On the contrary, except maleic acid, all other organic acids were detected in the leaves and roots of cabbages treated with nitrate deposition.

• Journal of Nutrition and Health
• /
• v.11 no.1
• /
• pp.9-16
• /
• 1978

A Comparison of the analysis of the green and roast coffee of Arabica and Robusta compositions and regular instant coffee has been investigated by chromatography. The coffee oil were obtained by extracting the green and roast coffee with ethyl ether by soxhlet methood. Instant coffee samples were accurately weighted into 100ml beaker (ca. 0.5g regular coffee and 1.5g decaffeinated coffee) and add ca. 50ml water, heat and boil, remove from heat, and mechanically stried ca. 15min. and filtered of one sample and another sample were without filtrated and proceed with liquid chromatographic separation. The fatty acid compositions of green and roast coffee were compared by gas liquid chromatography and general chemical compositions of sample were analysed. Some similarities between green and roast coffee fatty acids were found in the case of green and roast coffee of both kinds acid methyl esters. They contained stearic, oleic, linoleic, and unknown fatty acid, and palmitic ana linoleic acid were rich.

• Journal of the Korean Society of Tobacco Science
• /
• v.28 no.2
• /
• pp.67-74
• /
• 2006

This study was carried out to investigate the changes of essential oils in flue-cured leaf tobacco during aging for 21 months. The threshed leaf tobacco(BlO) produced in 2002 crop year was aged for 21 months in the warehouse of Oc-Cheon Leaf Tobacco Processing Factory. The leaf tobacco were sampled at three month intervals for analysis of volatile compounds. Volatile compounds were identified by GC/MS and comparison of gas chromatographic retention time with those of the authentic standard. The total of 75 compounds from the steam volatile concentrate of the flue-cured leaf tobacco were identified; they were 15 hydrocarbons, 12 alcohols, 3 aldehydes, 18 ketones, 7 esters, 10 acids, 3 phenols, 4 furans, 2 pyrrols and 1 pyridine. The major components of essential oil were neophytadiene, solanone, megastigmatrienone and phytol. After a aging period of 21 months, most of volatile compounds showed a gradual increasing tendency.

• Journal of the Korean Society of Tobacco Science
• /
• v.36 no.1
• /
• pp.26-33
• /
• 2014

Simultaneous determination of crop protection agents(CPAs) in food are done with multi-residue methods, which are composed of sample clean-up, concentration, chromatographic separation and detection. Stir Bar Sorptive Extraction(SBSE) technique is used for sample preparation of various analytes in several fields. The aim of this study was to develop a sensitive and fast method based on SBSE followed by thermal desorption - gas chromatography - mass spectrometry(TD - GC/MS) to determine CPAs in tobacco sample. For the analysis of tobacco sample prior to the SBSE method, solvent extraction or ultrasound-assisted solvent extraction was performed. methanol was used as the extraction solvent. The extract was then diluted with water. Finally, the sample was subjected to SBSE. A method for fast screening of crop protection agents in tobacco using SBSE-TD - GC/MS has been developed. About 17 CPAs including organochlorine, organophosphorous and others were identified and quantified. This method showed good linearity and high sensitivity for most of the target CPAs. The method was applied to the determination of CPAs at ng/mL levels in tobacco sample. This method is simple, rapid and may be applied in detection of other components.

• Journal of the Korean Chemical Society
• /
• v.34 no.4
• /
• pp.352-359
• /
• 1990

An effecient gas chromatographic method is described to be used routinely for the rapid profiling and identification of biochemically important organic acids. It involves the solid-phase extraction of organic acids from aqueous samples using Chromosorb P as the solid sorbent and diethyl ether as the eluting solvent, with subsequent triethylamine treatment. The resulting triethylammonium salts of acids were directly converted to volatile tert-butyldimethylsiyl derivatives, which were simultaneously analyzed by two capillary columns of different polarity, DB-5 and DB-1701, under the identical temperature programming condition. The retention index (RI) and area ratio (AR) values of each peak measured on DB-5 and DB-1701 enabled rapid identification of acids by computer RI library search and AR comparison. The application of the present method to the organic acid profiling of various complex samples is demonstrated.

• YAKHAK HOEJI
• /
• v.36 no.3
• /
• pp.191-198
• /
• 1992

The abuse of zipeprol, an antitussive agent, is prevalent among young people. Ten fatal cases of zipeprol concentration in blood after its abuse had caused death are disscussed. GC equipped with TSD was used to quantify the drug in postmortem blood and GC/MS to identify the metabolites in urine after preliminary test. The calibration curve of zipeprol was linear (r = 0.998) and the recoveries of zipeprol 5, 10 and $20\;{\mu}g$ added to 1 ml postmortem blood were $97.2{\pm}3.9$, $92.5{\pm}3.9$ and $86.9{\pm}4.6%$ respectively. The blood zipeprol concentration varied 2.9 to $24.69\;{\mu}g/ml$ in 10 fatal cases. All the deaths were young adults with the age of 16-21. Three metabolites were identified in drug abuser's urine, 2-methoxy-2-phenyl ethylpiperazine, 2-hydroxy-3-methoxy-3-phenyl propylpiperazine and a demethylated zipeprol.

• Journal of Biomedical Engineering Research
• /
• v.8 no.1
• /
• pp.29-40
• /
• 1987

2-Hydroxyethyl methacrylate(HEMA) was copolymerized with allyltrimethylsilane- (ATMS) and allylt.imethoxysilane(ATMOS) at 70。C in N, N'dimethylformamide- (DMV) using $\alpha$ , $\alpha$'-azobisisobutyronitrile(AIBN). The compositions of unreacted monomers were determined by gas chromatographic analysis. The monomer reactivity ratios were determined by Fireman-Ross, Helen-Tiidus and intersection methods. The average values are as follows : $$r_1(HEMA) : 6.62 $\pm$ 0.07, r_2(ATMS) : 0.07 $\pm$ 0.01 for HEMA-ATMS system.$$ $$r_l(HEMA) : 4.09 $\pm$ 0.14, r_2(ATMOS) : 0.06 $\pm$ 0.01 for HEMA-ATMOS toys tem.$$ The lower rl(HEMA) In the HEMA-ATMOS system as compared to HEMA ATMS system may be contributed to higher relative reactivity of ATMOS toward the poly(HEMA) radical. The compositions of synthesized copolymers were determined from silicon con tents estimated gravimetrically. The thermal stabilities of the copolymers were investigated by thermogravimetry(TG). The enthalpic changes associated with the endothermic transition were evaluated by differential scanning calorimetry(DSC). The swelling properties of the copolymers in water were also investigated.