• Analytical Science and Technology
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• v.17 no.3
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• pp.240-250
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• 2004

A gas chromatography-mass spectrometric (GC-MS) assay method was developed for the rapid and sensitive determination of volatile- and semivolatile organic compounds in water. Two hundreds mL of water sample was extracted in a 250 mL separatory funnel with 1 ml of pentane at pH 6.5. Fluorobenzene and 1,2-dichlorobenzene-d4 as internal standards were added to water sample and the solution was mechanically shaken for 5 min and analyzed by GC-MS (selected ion monitoring) without more any concentration or purification steps. The peaks had good chromatographic properties and the extraction of these compounds from water also gave relatively high recoveries with small variations. The range of detection limits of the assay was 0.5-10 ng/L. Turnaround time for up to about 40 samples was one day. This method is simple, convenient, and can be learned easily by relatively inexperienced personnel. This method was used to analyze 15 volatile- and semivolatile organic compounds in water of a Lake, and raw and treated water from three Water Treatment Plants in Korea. As the analytical results, benzene, toluene, xylene, isopropylbenzene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, naphthalene and 2,4,6-trichlorophenol were detected at concentrations of up to 0.4, 1.9, 1.3, 0.2, 1.8, 13.0, 1.7 and $1.1{\mu}g/L$, respectively. But chlorobenzene, trichloroethylene, tetrachloroethylene, ethylbenzene, n-butylbenzene and dibromochloropropane levels during that period were not significant. The removal effect of the compounds in three Water Treatment Plants was calculated. The compounds studied were generally removed during conventional water treatment, especially during the active carbon filtration.

• Journal of the Korean Chemical Society
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• v.48 no.2
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• pp.156-160
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• 2004

The extraction rates of plasticizer of LPG high pressure rubber are studied. Submerging solvents are composed of propane, n-butane, n-pentane, n-hexane, n-heptane, propylene, 1,3-butadiene, 1-pentene, 1-hexene, ethanethiol, t-butanethiol, dimethyl sulfide, methyl ethyl sulfide. The relationship between the extraction rate of plasticizer and the descriptors of submerging solvent by using multiple linear regression is as follows; PE(wt%) = 7.5193 - 0.58500Carbon${\sharp}$ + 2.3294DB + 2364SH, (N = 13, F = 24.135, R$^2$ = 0.8894, R$_{adj}^2$ = 0.8526, Variance = 7.588) Plasticizer is well extracted by LPG composed of the high vapour pressure and polarity compounds. The mass of extracted plasticizer becomes increasing in proportion to the contents of thiol sulfur compound and unsaturated hydrocarbon such as propylene and 1,3-butadiene in LPG. While the heavier hydrocarbons are, the less the quantities of plasticizer extracted from rubber are.

• The Korean Journal of Food And Nutrition
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• v.11 no.5
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• pp.493-498
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• 1998

An attempt was in this to analyzer volatile flavor components of sancho(Zanthoxylum schinfolium). Essential oils in sancho tree and fruit isolated by a simulataneous steam distillation (SDE) methods using n-pentane/diethyl ether as solvent. A total of 57 and 44 components were identified by gas chromatography(GC) and combined gas chromatography spectrometry (GC-MS), respectively. Granyl acetate(29.23%) geraniol (6.80%, p-isopropyl-2-chclohexenone(5.53%), phellandral (4.10%) in sancho fruit and 4, 6, 6-trimethyl-bicyclo(7.47%), T-carvelo(4.60%, ${\alpha}$-cypernone(3.58%) in sancho tree were found to be major volatile flavor. 22 compnents including myrcene, limonene, 1, 8-cinol in sancho fruit and 10 components including 4-(1-methylethyl)-cyclohexanol, methyl undecyl ketone in sancho tree were identified. The contents of unsaturated fatty acids of palmitic acid(24.34%), myristic acid(3,68%) in sancho tree was higher than that of the sancho fruit.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2002.04a
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• pp.65-69
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• 2002

Unsteady vaporization of a droplet quiescent in a high pressure environment are studied with emphasis placed oil the modeling of equilibrium at vapor-liquid interface. Complete set of conservation equations for liquid and gas phases is numerically time integrated. Vapor-liquid interfacial thermodynamics are solved by f]ash equilibrium calculation method. The model was proper]y validated with experiment and the improvement in the solution accuracy was made. Vaporization of n-pentane fuel droplet in nitrogen background gas is examined. Effects of ambient gas solubility, property variation, transient diffusion, and multicomponent transport on the droplet vaporization are investigated systematically. High-pressure effects on the droplet vaporization is examined and discussed.

• Journal of Nutrition and Health
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• v.15 no.1
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• pp.30-38
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• 1982

Experiments were carried out in order to compare the natural antioxidants in the acetonitril extracts of raw and baked seeds of Korean sesame and perilla by thin layer and gas chromatography. The sample was dissolved in n-pentane and extracted with acetonitril and the acetonitril extract was separated by thin layer chromatography using silica gel. The spots were detected by spraying with 2, 6 -dichloroquinone -4-chlorimide, phosphomolybdic acid and dimethylamine as chromogenic reagents. Natural antioxidant, such as ${\delta}-tocopherol$ detected in raw and baked sesame and perilla seed oil by TLC and sesamol was detected only in raw and baked sesame seed oil by GC.

• Journal of Environmental Health Sciences
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• v.19 no.2
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• pp.16-22
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• 1993

In recent years, great concern for the improvement of drinking water quality has been arising due to the contamination of the raw and treated water. So trihalomethanes (THMs) and some other volatile organic compounds (VOCs), potential carcinogenic substances, rendered the government to take some countermeasurements for clean water service in the dimension of public health. In this study, we used liquid-liquid extraction method as a rapid simple method for determination of VOCs through eluation with n-Pentane in water. The aim with the present study has been to determine the changes of recovery and reproducibility of the method under the various conditions in extraction solvents, solvent ratio and extraction time, and to observe the concentrations under the various temperature and pH during storage.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.2
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• pp.188-191
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• 2000

Appetite stimulant ether-soluble neutral extract of a high-grain compound feed was separated into four fractions with an open column of silica gel chromatograph using four carrier solutions containing n-pentane and diethyl ether as 100:0 (Fraction A), 90:10 (Fraction B), 75:25 (Fraction C) and 0:100 (Fraction D). The stimulative effects of the fractions were examined by comparing the intake of hay (with or without the fractions) in two-choice test bioassays with cattle. The Fractions A, B and C of the neutral extract stimulated (p<0.05) hay consumption in cattle, whereas Fraction D had no effect on selective feeding when compared with the control fraction. Furthermore, Fractions A, B and C had higher (p<0.05) feeding stimulative indices (FSI) than that of the Fraction D. The results suggest that chemical stimulants to increase palatability of hay are present in the neutral Fractions A, B and C of high-grain concentrate.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.4
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• pp.563-567
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• 1998

Volatile flavor components of edible portion of leek(Allium tuberosum R.) were extracted by SDE(simultaneous steam distillation and extraction) method using the mixture of n-pentane and diethylether (1 : 1, v/v) as an extract solvent and analyzed by GC-FID and GC/MS. Identification of the volatile flavor components was mostly based on the RI of GC and mass spectrum of GC/MS. A total of sixty-five components from leek extract were classified as 28 sulfur-containing compounds, 12 aldehydes, 9 alcohols, 4 lactones and esters, 3 acids and hydrocarbons, and 2 miscellaneous compouds. The sulfur-containing compounds were predominant in leek extract. Dimethyl disulfide(19.47%) and dimethyl trisulfide(17.38%) were the main compounds and trans-1-propenyl methyl disulfide, trans-2-hexenal and methyl allyl disulfide were also detected large amounts in leek.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1286-1291
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• 2004

In order for studying pressure-coupled dynamic responses of droplet vaporization, open-loop experiment of an isolated droplet vaporization exposed to pressure perturbations in stagnant gaseous environment is numerically conducted. Governing equations are solved for flow parameters at gas and liquid phases separately and thermodynamic parameters at the interfacial boundary are matched for problem closure. For high-pressure effects, vapor-liquid interfacial thermodynamics is rigorously treated. A series of parametric calculations in terms of mean pressure level and wave frequencies are carried out employing a n-pentane droplet in stagnant gaseous nitrogen. Results show that wave instability in view of pressure-coupled vaporization response seems more susceptible at higher pressures and higher wave frequencies. Mass evaporation rate responding to pressure waves is amplified with increase in pressure due to substantial reduction in latent heat of vaporization. Augmentation of perturbation frequency also enhances amplification due to the reduction of phase differences between pressure perturbation and surface temperature fluctuation.

• Proceedings of the Korean Biophysical Society Conference
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• 1999.06a
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• pp.56-56
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• 1999

Change of membrane property can affect the activity of membrane proteins. In this work, we investigated the single channel properties of large conductance $Ca^{2+}$-activated $K^{+}$(BK) channels in planar lipid bilayers of different thickness. First, we recorded the activity of single BK channels from rat skeletal muscle incorporated into the control bilayer, then increased the bilayer thickness by perfusing the recording solution with the one saturated with n-pentane, or reduced the thickness by adding diheptanoylphosphatidylcholine (di$C_{7:0}$PC) to the recording soluton.(omitted)