• Korean Journal of Food Science and Technology
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• v.34 no.5
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• pp.905-910
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• 2002

4-Hydroxyalkenals are cytotoxic aldehydes generated by the oxidation of n-6 and n-3 polyunsaturated fatty acids. To evaluate the potential risk of 4-hydroxyalkenals on Koreans, quantitative data of various oils are necessary. Simultaneous monitoring of 4-hydroxyhexenal and 4-hydroxynoneal in 39 samples including new and used ones through single ion monitoring mode of GC/MS detected both aldehydes in all samples tested, ranging from 0.21 to 26.9 nmol/g for 4-hydroxy-2-hexenal and 0.06 to 56.6 nmol/g for 4-hydroxy-2-nonenal. Frying oils collected from local markets showed 2.28-7.90 and 8.31-30.5 nmol/g of 4-hydroxyhexenal and 4-hydroxynoneal, respectively. National health and nutrition survey data were employed to determine the exposure effect to these 4-hydroxyalkenals from the four most consumed oils in Korea. Daily exposures to hydroxyalkenals excluding possible exposure from fried food were $1.9\;{\mu}g$ from soybean oil, $0.5\;{\mu}g$ from sesame oil, $0.2\;{\mu}g$ from corn oil, and $0.1\;{\mu}g$ from perilla oil. Due to the increasing consumption of polyunsaturated fatty acids in Korea, these data may provide valuable information for evaluating possible physiological effects of 4-hydroxyalkenals from vegetable oils.

• Journal of the Korean Chemical Society
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• v.38 no.11
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• pp.819-826
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• 1994

This study described a simple, rapid and cost effective analytical technique for the ultra-trace analysis of dioxins in environmental samples. Liquid-Liquid extraction methods were used for the initial extraction and enrichment of the analyte. Subsequent clean-up procedures were achieved by using strong cation exchanger, silica and Florisil cartridges. Extracts were analysed by HRGC/HRMS-SIM. The efficiency of these analytical methods was tested by recovery and selectivity for elimination of interferences such as phenols, pesticides and PCBs in each step. The mean recovery of 1,2,3,4-TCDD spiked at 10 ppt in sea water was about 92(${\pm}$1.6)%. This analytical method was applied to Kwangyang sea water and 4.5pg/L of 2,3,7,8-TCDD was determined.

• Journal of Environmental Science International
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• v.17 no.5
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• pp.479-484
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• 2008

The application of microwave technology has been investigated in the remediation of diesel-contaminated soil. The paper deals with economic assessment by means of cost analysis and degradation characteristics at different microwave powers for total petroleum hydrocarbon (TPH) in diesel contaminated soils. The soils from S Mountain around the D University were sampled. The samples were screened with 2.0 mm mesh and dried for 6 hours before the diesel was added into the dried soils. The diesel-contaminated soil (3,300 mg THP/kg soil) was prepared with diesel (S Co.). The drying process was carried out in a microwave oven, a standard household appliance with a 2,450 MHz frequency and 700 W of power. The experiments were conducted from 0 to 20 minutes as the microwave powers increased from 350W to 500W to 700W. The concentrations of TPH were analysed using a gas chromatography/mass spectrometer (GC/MS). The initial concentration of TPH was 3,300 mg TPH/kg soil. The weight of contaminated soil was 200g. The concentration of TPH was decreased to 1,828 mg TPH/kg soil (44.7%), 1,347 mg TPH/kg soil (59.2%) and 1,014 mg TPH/kg soil (69.3%) at 350W, 500W and 700W for 15 minutes respectively. In addition, the curve was best fit with first order kinetics using the least-square method. The ranges of a first order rate constant k and r-square were $0.0298{\sim}0.0375min^{-1}$ and $0.9373{\sim}0.9541$ respectively.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.225-228
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• 2002

Amorphous $Ga_2O_3$ films have been grown on Si(100) substrates by metal organic chemical vapor deposition (MOCVD) using gallium isopropoxide, $Ga(O^iPr)_3$, as single precursor. Deposition was carried out in the substrate temperature range 400-800 $^{\circ}C$. X-ray photoelectron spectroscopy (XPS) analysis revealed deposition of stoichiometric $Ga_2O_3$ thin films at 500-600 $^{\circ}C$. XPS depth profiling by $Ar^+$ ion sputtering indicated that carbon contamination exists mostly in the surface region with less than 3.5% content in the film. Microscopic images of the films by scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed formation of grains of approximately 20-40 nm in size on the film surfaces. The root-mean-square surface roughness from an AFM image was ${\sim}10{\AA}$. The interfacial layer of the $Ga_2O_3$/Si was measured to be ${\sim}35{\AA}$ thick by cross-sectional transmission electron microscopy (TEM). From the analysis of gaseous products of the CVD reaction by gas chromatography-mass spectrometry (GC-MS), an effort was made to explain the CVD mechanism.

• Journal of the Korean Society of Tobacco Science
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• v.28 no.2
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• pp.136-143
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• 2006

This study was conducted to determine the amount of unprotonated nicotine in cigarette mainstream smoke and to investigate its relationship to level of filter ventilation and machine smoking conditions. Unprotonated nicotine from TPM trapped on a Cambridge filter pad(CFP) was adsorbed by Carboxen/PDMS SPME fiber, thermally desorbed and determined by GC/MS. 2R4F reference cigarette, twelve commercial brands from the Korean market and five test cigarette samples, which had the same tobacco blend with different levels of filter ventilation, were analyzed for unprotonated nicotine. In commercial brands, the amount of unprotonated nicotine changed slightly depending on the pH values of smoke, and decreased as the tar level increased. filter ventilation in these commercial cigarettes was $28{\sim}80%$ and the higher filter ventilation increased relative unprotonated nicotine levels, but not significantly. However, in five test cigarettes with different filter ventilation$(0{\sim}70%)$, unprotonated nicotine levels increased almost linearly with the level of filter ventilation. Concentrations of unprotonated nicotine in mainstream smoke generally increased in order $HC\;<\;ISO\;{\leq}\;MDPH$ machine smoking conditions. The ratio of unprotonated nicotine to total nicotine among $cigarettes({\alpha}_{fb})$ increased in order RC < MDPB < ISO conditions. Concentrations of unprotonated nicotine varied with three machine smoking conditions.

• Tribology and Lubricants
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• v.33 no.6
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• pp.263-268
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• 2017

The significance of maintaining the soil environment is gradually increasing owing to soil and underground water contamination by petroleum leak accidents. However, the purification of soil is an expensive and more time-consuming process than the purification of contaminated water and air. Moreover, determining the source and people responsible for soil pollution gets often embroiled in legal conflicts, further delaying the cleanup process of the contaminate site. Generally, TPH (total petroleum hydrocarbon) pattern analysis is used to determine the petroleum species and polluter responsible for soil contamination. However, this process has limited application for petroleum products with a similar TPH pattern. In this study, we analyze the TPH pattern and specific sectional ratio (${\sim}C_{10}$, $C_{10}-C_{12}$, $C_{12}-C_{36}$, and $C_{36}{\sim}$) of various domestic petroleum products to identify the petroleum product responsible for soil contamination. Also, we perform BTEX (benzene, toluene, ethyl benzene, xylene) quantitative analysis and determine B:T:E:X ratio using GC-MS. The results show that gasoline grade 1 and 2 have a similar TPH pattern but different BTEX values and ratios. This means that BTEX analysis can be used as a new method to purify soil pollution. This complementary TPH and BTEX method proposed in this study can be used to identify the petroleum species and polluters present in the contaminated soil.

• Journal of Crop Science and Biotechnology
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• v.10 no.4
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• pp.281-286
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• 2007

Gibberellins are growth hormones that play a pivotal role in the growth and development of plants. Present investigations were carried to check the effect of nitrogen(N) and silicon(Si) on bioactive $GA_1$ and its immediate precursor $GA_{20}$ at different growth stages of two rice cultivars with different maturity traits. It was observed that the endogenous bioactive $GA_1$ level gradually increased during vegetative stage and anthesis stage of both Junghwabyeo(early flowering cultivar) and Daesanbyeo(late flowering cultivar). However, the $GA_1$ and $GA_{20}$ content start decreasing during the seed filling stage in both rice cultivars, which indicated a possible relationship of bioactive $GA_1$ and floral development. Our results also confirmed that early 13-hydroxylation pathway was operated at all developmental stages of rice plant. Variation in the levels of the endogenous gibberellins in rice shoots were measured by GCMS-SIM using $^2H_2$-labeled gibberellins as internal standards. Combined application of N and Si enhanced growth parameters and reduced lodging index of both rice cultivars. It was thus concluded that the level of physiologically active $GA_1$ increased during vegetative and early reproductive stage, but starts declining at seed filling stage.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.9
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• pp.1013-1019
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• 2007

Electronic wastes have increased tremendously. However, any reliable treatment methodologies have rarely been established. Electronic wastes have posed serious disposal problem due to their physico-chemical stability. This paper investigated the application possibility of pyrolysis for the purpose of recycling the p-CCL(phenol based Copper Clad Laminate). Thermogravimetric analysis(TGA) was used to investigate the thermal decomposition pattern of p-CCL. We elucidated the characteristics of pyrolysis by-products at operating temperatures of 280, 350 and $600^{\circ}C$. GC/MS and FT-IR were used to characterize the liquid by-products along with general characterization methods such as Ultimate Analysis, Proximate Analysis and Heating Value, whereas general characterization methods were only introduced for the solid by-products. At a heating rate of $5^{\circ}C$/min, TGA curves exhibited three decomposition stages: (1) low-temperature decomposition region$(<280^{\circ}C)$, (2) medium temperature region$(280\sim350^{\circ}C)$ and (3) high-temperature region$(>350^{\circ}C)$. The major compounds of liquid by-products at low- and medium-temperatures were accounted for by water and phenol, whereas branched phenols and furans were major compounds at high-temperatures. As the temperature increases, volatile quantities decreased but the fixed carbon increased. High heating values of solid by-products($7,400\sim7,600$ kcal/kg) would suggest that the solid by-products could be applicable as fuel. In addition, high fixed carbon but low ash content of the solid by-products offered an implication that they are capable of being upgradable for adsorbent after applying appropriate activating process.

• Korean Journal of Food Science and Technology
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• v.33 no.3
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• pp.366-372
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• 2001

Volatile flavor components in the mash of Takjus prepared by using Aspergillus oryzae nuruk were identified by using Gas Chromatography and Gas Chromatography-Mass Spectrometry. Twenty-four esters, 21 alcohols, 10 acids, 9 aldehydes and 4 others were found in the mash of Takju. Thirty six components including 13 esters and 12 alcohols were detected in the beginning of fermentation. Twenty nine components were more detected after second day of fermentation and 68 components were detected after 12 days of fermentation. Thirty five flavor components including 12 alcohols such as ethanol, 2-methyl-1-propanol, 3-methyl-1-butanol and benzeneethanol, 13 esters such as ethyl acetate, ethyl caprylate, ethyl butyrate and isoamyl acetate, 4 aldehydes and 6 acids were usually detected in the fermentation process. Ethanol was predominantly found in the range of $79.86{\sim}89.54%$ as a major component by using relative peak area. 3-Methyl-1-butanol, ethyl caprylate and benzeneethanol were some of the major volatile components through the fermentation respectively. Peak area of 2-methyl-1-propanol, 1-hexanol, 1-dodecanol, ethyl acetate, monoethyl butanoate, acetic acid and isobutylaldehyde among the same group were higher than other components depending upon fermentation time.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.102-110
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• 2000

Peeled garlic was stored at $-18^{\circ}C\;and\;-40^{\circ}C$, respectively and changes in main quality factors during storage were determined for $15{\sim}16$ months. The puncture force measured by texturemeter was $2709{\pm}368$ G.S at the beginning of storage and did not change significantly after the 15 months storage. Drip losses of stored garlic were 0.4% and 0.7% at $-18^{\circ}C\;and\;-40^{\circ}C$, respectively. Major flavor compounds of garlic analyzed by GC and GC/MS, such as diallyl disulfide, 1,3-dithiane, diallyl sulfide, 2-butanal, were not changed in their quantity during the frozen storage. The contents of cysteine, valine and tyrosine increased slightly notwithstanding the storage temperature. Sucrose content slightly decreased, but glucose and fructose tended to increase in garlic stored at $-18^{\circ}C$. The content of pyruvic acid, degradation product of alliin, did not change during storage at both storage temperatures. These results indicated that peeled garlic could be stored at $-18^{\circ}C$ for longer than 15 months without quality problems.