• Korean Journal of Environmental Agriculture
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• v.13 no.2
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• pp.199-208
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• 1994

Analytical methods for the determination of the derivatives of the herbicide (${\pm}$)-2-(4-chloro-2-methylphenoxy)propionic acid (MCPP) by capillary column gas chromatography with mass spectrometer (GC-MS) and electron-capture detection (GC-ECD) were studied. A successful procedure was introduced for the ester preparation using $H_2SO_4$, as the catalyst and the alcohol 2,2,2-trichloroethanol (TCE) or 2,2,2-trifluoroethanol (TFE). The identificaiton and elucidation of MCPP by GC-MS spectrometry following the esterification with diazomethane, $BF_3$/methanol, $H_2SO_4$/methanol, TCE, TFE, or pentafluorobenzyl bromide (PFB) were carried out. A comparison of the response-sensitivities among those MCPP esters was made with GC-ECD. Although the methylation product of MCPP was confirmed by GC-MS, its low sensitivity to the ECD limited the detection of MCPP. TCE, TFE, and PFB derivatization methods resulted in a high rate of MCPP esterifications and very sensitive ECD molecular responses. Based on efficiency, convenience, worker safety, and least sample contamination, TFE esterificaiton was considered as the superior method for MCPP analysis to the other methods of derivatization. An accurate method is described for quantifying MCPP in soil leachates by GC-ECD at very low concentrations without the requirement of a complicated clean-up process. As a result, MCPP residues at concentrations of less than $0.1{\mu}g$ in 100ml soil leachate were detected.

• Korean Journal of Environmental Agriculture
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• v.31 no.2
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• pp.146-151
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• 2012

BACKGROUND: This study was conducted to develop analytical method for picoxystrobin in agricultural commodities using GC/ECD and GC/MS. METHODS AND RESULTS: Each steps of analytical method were optimized for determining picoxystrobin residues in various agricultural commodities. The developed methods include acetone extraction, n-hexane/saline water partition and florisil column chromatography for analysis of all samples (apple, potato, green pepper, hulled rice and soybean), and in addition to these steps, solid phase extraction (SPE) was used for analysis of green pepper and n-hexane/acetonitrile partition was used for analysis of hulled rice and soybean. The instrumental conditions were tested for quantitation in GC/ECD and for confirmation in GC/MS. Recovery was in the range of 86~109% with RSD ${\leq}$10.2% and the quantitation limits (LOQ) of method were 0.025 mg/kg in all agricultural commodities. CONCLUSION: The result showed that the developed method can be used to determine picoxystrobin residue in agricultural commodities.

• Food Science and Industry
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• v.51 no.1
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• pp.16-25
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• 2018

Recently, the importance of analytical techniques related to food safety is emerging in the food industry due to changes in diet patterns, environmental changes, climate change and consumer's interest in food safety. In particular, food safety accidents in the food industry may cause economic losses such as media reports, product recalls, consumer distrust, and so on. Therefore, a systematic, proactive and comprehensive food safety management system is increasingly required to prevent food safety issues. Efforts to ensure the reliability of food safety are essential by introducing various analysis instruments such as LC, GC, ICP, LC/MS/MS, GC/MS/MS, ICP/MS, PCR, and RT-PCR. In addition, recent food safety analytical techniques used in food industry should be shifted paradigm by developing multi-component simultaneous analytical method, low cost with high efficient analytical method, and eco-friendly method.

• Analytical Science and Technology
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• v.17 no.2
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• pp.117-129
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• 2004

Amitrole in environment, difficult to be analyzed by GC or GC/MS due to high polarity and low volatility, was analyzed by LC/ESI/MS in the study. Maximum peak intensity of amitrole in LC/MS/ESI mass spectrum is m/z 85 of protonated molecular ion $(M+H)^+$ with 30V of cone voltage at SIR mode. It was confirmed that ratios between main ion of amitrole, 85 of protonated molecular ion, and m/z 58 fragmented ion of amitrole, had increased corresponding with the increment of cone voltage from 20V to 70V. The isotope molecular weight of amitrole was $86([M+H])^+$ at LC/MS analysis and the mass spectrum ratio between 85 mass and 86 mass was not different by the change of concentration but similar to theoretical ratio(less than 10% standard deviation).The linearity of standard calibration curve under same condition with sample treatment method had $y=1.09354e^6X+26947.2$ and $r^2=0.99$. Recovery rates in water and soil samples were 77.64~83.44% and 71.11~79.44%, respectively. Reliability of the analysis was performed with 5 repeated measurements at each level of standard concentration and the result showed that relative standard deviation was less than 10%; therefore, the extraction and analysis method in the study suggested that it would be reliable to measure amitrole in water and soil media.

• Journal of the Korean Society of Food Culture
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• v.21 no.3
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• pp.319-324
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• 2006

Volatile compounds in low-temperature and long-term fermented Baechu kimchi were extracted by high vacuum sublimation(HVS), and then analyzed by gas chromatography/mass spectrometry(GC-MS). A total of 62 compounds, including 7 sulfur-containing compounds, 8 terpenes, 5 esters, 8 acids, 15 alcohols, 2 nitrites, 2 ketones, 11 aliphatic hydrocarbons and 4 miscellaneous compounds, were found in low-temperature and long-term fermented Baechu kimchi. Among them, acetic acid and butanoic acid were quantitatively dominant. Aroma-active compounds were also determined by gas chromatography/olfactometry(GC-O) using aroma extract dilution analysis(AEDA). A total of 16 aroma-active compounds were detected by GC-O. Butanoic acid was the most potent aroma-active compound with the highest FD factor($Log_3FD$) followed by linalool, acetic acid, 2-vinyl-4H-1,3-dithin and 3-methyl-1-butanol. The major aroma-active compounds, such as acetic acid and butanoic acid, were related to sour and rancid or notes.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.22 no.2
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• pp.45-55
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• 2017

Long chain alkyl diols (LCDs) have been reported in sediments from various marine environments. Rampen et al. (2012) introduced the paleo-sea surface temperature (SST) proxy, Long chain Diol Index (LDI) based on the relative abundance of $C_{30}$ 1,15-diol, $C_{28}$ 1,13-diol, and $C_{30}$ 1,13-diol. In general, CP-Sil5CB and DB-5ms columns have been used for the quantitative and qualitative analysis of LCDs with a GC-MS. In this study, we examined the effect of three different columns (CP-Sil5CB, HP-5ms and DB-5) on the quantitative analysis of LCDs using marine sediments from the East Sea of Korea and the western Arctic Ocean. In general, our study showed that the results of CP-Sil5CB differed significantly from those of HP-5ms and DB-5. However, the differences of the LDI-derived SSTs among three columns were $0.1-0.2^{\circ}C$ for the East Sea and $0.2-0.7^{\circ}C$ for the western Arctic Ocean, which were well within the calibration error range (${\pm}1{\sigma}$). Accordingly, our study showed that the use of different columns resulted in significant differences of LCDs concentrations, but its effect on the LDI was relatively insignificant. Therefore, it appears that the different columns can be used for the paleo-SST reconstruction in the East Sea and the western Arctic Ocean using the LDI proxy.

• Journal of Life Science
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• v.21 no.5
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• pp.706-712
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• 2011

Metabolism of $^3H$-castasterone in the presence of $^{32}P$-ATP was examined by an enzyme solution prepared from A. thaliana after a reversed phased HPLC, after which a polar metabolite labeled by both $^3H$ and $^{32}P$ was obtained, suggesting that $^3H$-CS is phosphorylated by $^{32}P$-ATP. To elucidate the structure of the phosphorylated CS, the same enzyme assay was carried out with non-isotopes labeled CS and ATP. In GC-MS analysis the metabolite gave a molecular ion at m/z 664 as a bismethanboronate, suggesting the metabolite is a CS phosphate. Treatment of wheat germ acid phosphatase that hydrolyzed phosphoester bond gave the same mass spectrum and GC retention time in GC-MS analyses, confirming that the metabolite is phosphorylated CS. This is the first example of phosphorylated conjugates of CS in plants.

• Journal of the Korean Society of Tobacco Science
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• v.16 no.2
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• pp.172-180
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• 1994

This study was carried out to separate and identify the acidic compounds in tobacco leaves. Izmir tobacco leaves was extracted with isopropyl ether and the extract was concentrated. The concentrate was extracted with 6% NaHCO3 aqueous solution. The aqueous extract was acidified with sulfuric acid, and extracted with diethyl ether. The acidic material was fractionated on silicic acid column using a benzene-methanol mixture with a stepwise increasing methanol concentration. The resulting fractions were esterified with diazomethane, and then identified by GC, GC/MS using SPB -5 fused silica capillary column. Most of acidic compounds in Izmir tobacco leaves were elected from fraction B which was benzene-methanol(98 : 2) mixture on silicic acid column chromatography. The identified acidic compounds of Izmir tobacco leaves were 18 saturated acids, 8 unsaturated acids, 5 dicarboxylic acids, 13 aromatic acids and 7 terpenoid acids. The major acidic compounds of lzmir tobacco leaves were 2- methylbutanoic, 3-methyl butanoic, 3- methylpentanoic, hexanoic, nonanedioic, phenylacetic, benzoic, 4- methoxybenzoic, 3, 5- dimethoxybenzoic, methoxycinnamic and 3, 4- dimethoxycinnamic acid. Key Words : Izmir tobacco, Acidic compounds, GC/MS.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.593-595
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• 1993

The volatile components of garlic extracts were investigated. For experiment both crushed- and sliced-garlic were dried by air-drying and freeze-drying methods, followed by ether extraction. The extracts were analysed by GC and GC/MS. Sliced- and freeze-dried garlic extracts showed larger number of volatile components than crushed- and air-dried garlic extracts. The volatile components, allyl propyl disulifde, 2-vinyl-1,3-dithiane, 3-vinyl-〔4H〕-1,2-dithiin, 1,2-Bis (allyl)disulfane were found in sliced- and freeze-dried garlic extracts, methyl allyl trisulfide and 2,4-methyl furane in sliced- and air-dried garlic extracts, and disulfide in crushed- and air-dried garlic extracts.

• Journal of Food Hygiene and Safety
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• v.28 no.2
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• pp.130-137
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• 2013

In this study, we investigated the applicability of the photostimulated luminescence (PSL), thermoluminescence (TL), electron spin resonance (ESR) and gas chromatography/mass spectrometry (GC/MS) methods for 5 seeds which are not allowed to be irradiated in Korea. All 5 seeds including evening primrose seed, safflower seed, rape seed, sunflower seed and flax seed were analyzed. Samples were irradiated at 1~10 kGy using a $^{60}Co$ gamma-ray irradiator. In PSL study, the photon counts of all the unirradiated samples showed negative (lower than 700). The photon counts of irradiated (1, 5, 10 kGy) samples showed positive (higher than 5,000). In TL analysis, results showed that it is possible to apply TL method to all foods containing minerals. In ESR measurements, the ESR signal (single-line) intensity of irradiated foods was higher than non-irradiated foods. The hydrocarbons 1,7-hexadecadiene ($C_{16:2}$) and 8-heptadecene ($C_{17:1}$) from oleic acid were detected only in the irradiated samples before and after the treatment at doses ${\geq}$ 1 kGy, but they were not detected in non-irradiated samples before and after treatment. These two hydrocarbons could be used as markers to identify irradiated safflower seed, rape seed, Sunflower seed and flax seed. And then, the hydrocarbons 1,7,10-hexadecatriene ($C_{16:3}$) and 6,9-heptadecadiene ($C_{17:2}$) from linoleic acid were detected in the evening primrose seed, safflower seed and sunflower seed. According to the results, PSL, TL and GC/MS methods were successfully applied to detect the irradiated foods. It is concluded that PSL, TL and GC/MS methods are suitable for detection of irradiated samples and a combined method is recommendable for enhancing the reliability of detection results.