• Journal of Environmental Science International
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• v.23 no.6
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• pp.1037-1047
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• 2014

A highly sensitive analytical method based on stir bar sorptive extraction (SBSE) technique and gas chromatography/tandem mass spectrometry (GC/MS-MS) has been developed, allowing the simultaneous multi-analyte determination of seven UV filters in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 40 mL of water sample at pH 3 and stirred at 1,100 rpm for 120 min. Other SBSE parameters (salt effect and presence of organic solvent) were optimised. The method shows good linearity (coefficients > 0.990) and reproducibility (RSD < 12.9%). The extraction efficiencies were above 84% for all the compounds. The limits of detections (LOD) and limits of quantification (LOQ) were 2.1~8.6 ng/L and 6.8~27.5 ng/L, respectively. The developed method offers the ability to detect 8 UV filters at ultra-low concentration levels with only 40 mL of sample volume. Matrix effects in tap water, river water, wastewater treatment plant (WWTP) final effluent water and seawater were investigated and it was shown that the method is suitable for the analysis of trace level of 7 UV filters except of benzophenone (BP). The method developed in the present study has the advantage of being rapid, simple, high-sensitive and both user and environmentally friendly.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.11
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• pp.764-770
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• 2014

This study assessed analysis of N-nitrosamines by separation, identification, and quantification using a gas chromatography (GC) mass spectrometer (MS) with electron impact (EI) mode. Samples were pretreated by a automated solid phase extraction (SPE) and a nitrogen concentration technique to detect low concentration ranges. The analysis results by EI-GC/MS (SIM) and EI-GC/MS/MS (MRM) on standard samples with no pretreatment exhibited similar results. On the other hand, the analysis of pretreated samples at low concentrations (i.e. ng/L levels) were not reliable with a EI-GC/MS due to the interferences from impurity peaks. The method detection limits of eight (8) N-nitrosamines by EI-GC/MS/MS analysis ranged from 0.76 to 2.09 ng/L, and the limits of quantification ranged from 2.41 to 6.65 ng/L. The precision and accuracy of the method were evaluated using spiked samples at concentrations of 10, 20 and 100 ng/L. The precision were 1.2~13.6%, and the accuracy were 80.4~121.8%. The $R^2$ of the calibration curves were greater than 0.999. The recovery rates for various environmental samples were evaluated with a surrogate material (NDPA-$d_{14}$) and ranged 86.2~122.3%. Thus, this method can be used to determine low (ng/L) levels of N-nitrosamines in water samples.

• Korean Journal of Food Science and Technology
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• v.19 no.3
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• pp.279-284
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• 1987

Volatile components of Artemisia selengensis and Cryptotaenia japonica. Korean wild vegetables, were collected by steam distillation. Samples were examined by gas chromatography (GC) and combinded gas chromatography-mass spectrometry (GC-MS). Seven components of ${\alpha}-pinene$, camphene, ${\beta}-pinene$, myrcene limonene, r-terpinene, and caryophyllene, and two components of ${\alpha}-pinene$ and ${\beta}-pinene$ were confirmed respectively in Artemisia selengensis and Cryptotaenia japonica. The remaining components are presumed to be elemene, caryophyllene, and humulene in the latter.

• Applied Biological Chemistry
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• v.31 no.4
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• pp.394-399
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• 1988

Volatile components of Ixeris dentata and Amaranthus mangostanus, Korean wild vegetables, were collected by Steam Distillation-Extraction(SDE) method. Essential oils were analyzed by gas chromatography(GC)and combined gas chromatography-mass spectrometry(GC-MS). Sixty one components, including 13 alcohols, 9 esters, 12 aldehydes, 6 ketones, 9 hydrocarbons, 6 acids, 3 phenols and 3 miscellaneous ones were confirmed in Ixeris dentata. Fifty six components, including 15 alcohols, 5 esters, 13 aldehydes, 8 ketones, 3 hydrocarbons, 9 acids and 5 miscellaneous ones were confirmed in Amaranthus mangostanus.

• Korean Journal of Food Science and Technology
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• v.25 no.5
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• pp.494-501
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• 1993

The volatile flavor components of traditional and commercial kochujang were collected by simultaneous steam distillation-extraction (SDE) method. Essential oils were analyzed by gas chromatography (GC) and combined gas chromatography-mass spectrometry (GC/MS). Tested kochujang included Sunchang kochujang prepared with glutinous rice, Boeun kochujang prepared with barley, Sachun kochujang prepared with wheat and commercial kochujang. One hundred and twelve volatile flavor components which included 30 esters, 15 alcohols, 14 aldehydes, 13 acids, 9 ketones, 7 alkenes, 6 phenols, 3 alkanes, 3 pyrazines, 2 benzenes and 2 furans were identified. The major volatile compounds in traditional and commercial kochujang were 2-methyl propanal and ethanol, which represented $21{\sim}36%\;and\;2{\sim}44%$ of total GC peak area, respectively.

• Journal of the Korean Society of Food Culture
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• v.3 no.2
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• pp.207-210
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• 1988

Volatile components of Artemisia keiskeana, Korean wild vegetable, were collected by steam distillation. Samples were analyzed by gas chromatography(GC) and combined gas chromatography-mass spectrometry(GC-MS). Twenty nine components, including 17 hydrocarbons, 6 alcohols, 2 aldehydes, 1 oxide, and 3 furans were confirmed in this study.

• Analytical Science and Technology
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• v.25 no.6
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• pp.467-475
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• 2012

A gas chromatography-mass spectrometric (GC-MS) method was developed for determining 17 hazard compounds containing phenols, polycyclic aromatic hydrocarbons and pesticides in surface water. A 1.0 L surface water sample was placed in a separatory funnel and saturated with NaCl, and the solution was extracted with 40 mL of methylene chloride. Under the established condition, the lowest quantification limit was 1.0-10 ng/L and the relative standard deviations were less than 22%. The method was used to analyze 70 surface water samples collected from 35 regions in Gum-River. The samples revealed the compounds concentrations in the range of 1.1-26,604 ng/L. Maximum concentrations of compounds detected were not exceeded guidelines established in other countries. The developed method may be valuable for monitoring hazards in water.

• Analytical Science and Technology
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• v.25 no.1
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• pp.60-68
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• 2012

A gas chromatography-mass spectrometric (GC-MS) method was developed for determining 25 semivolatile organic compounds in water. A 1.0 L water sample was placed in a separatory funnel and saturated with NaCl, and the solution was extracted two times with 40 mL of methylene chloride. Under the established condition, the linear quantification range was 0.02-800 ng/L and the relative standard deviation was less than 15%. The method was used to analyze 16 surface water samples collected from various regions in Gum-River. The samples revealed SVOC concentrations in the range of 0.02-96.8 ng/L. Maximum concentrations of VOCs detected were not exceeded the EPA or Germany guidelines in any of the samples. The developed method may be valuable for monitoring SVOCs in water.

• Mass Spectrometry Letters
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• v.3 no.1
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• pp.21-24
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• 2012

$5{\alpha}$-Dihydrotestosterone (DHT) is the primary active metabolite of testosterone, catalyzed by $5{\alpha}$-reductase ($5{\alpha}R$) in the skin, prostate, and liver. In this study, the $5{\alpha}R$ activity in rat liver S9 fraction in the presence of a NADPH-generating system was evaluated and compared by gas chromatography-mass spectrometry (GC-MS)-based in vitro assays. Testosterone and a $5{\alpha}R$ inhibitor, finasteride, were added to the S9 fractions and incubated at $37^{\circ}C$ for 1 h. Both testosterone and DHT were quantitatively measured and compared with two different GC-MS-based steroid profiling techniques. DHT was not detected by conventional GC-MS analysis in the absence of finasteride when the concentration of testosterone in the S9 fraction was less than $0.2{\mu}M$, whereas the isotope-dilution GC-MS (GC-IDMS) system was able to evaluate the $5{\alpha}R$ activity. Because the S9 fraction contains more reactive enzymes and is easier to collect from tissues compared with a microsomal solution, the combination of the S9 fraction and GC-IDMS technique may be a promising assay for evaluating the $5{\alpha}R$ activity in large-scale clinical studies.

• Preventive Nutrition and Food Science
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• v.7 no.1
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• pp.5-11
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• 2002

The comparison of the volatile flavor components from Korean and Japanese Satsuma mandarin (C. unshiu Marcov. forma Miyagawa-wase) peel oils, isolated by cold-pressing, was performed by gas chromatography, mass-spectrometry and gas chromatography-olfactometry (GC-O). Eighty-five volatile components were identified in each oil by GC and GC-MS. Forty-three components were detected in each oil by GC-O. The total amount of monoterpene hydrocarbons was 95.88% (Korean mandarin) and 95.29% (Japanese mandarin). Limonene, ${\gamma}$-terpinene, myrcene and $\alpha$-pinene were the main components of the cold-pressed oils from the both samples. The volatile composition of the Japanese mandarin was characterized by a higher content of sesquiterpene hydrocarbons, especially bicyclogermacrene, $\alpha$-humullene and valencene. The volatile composition of two samples can easily be distinguished by the percentages of aldehydes, ketones and esters, which were found at higher levels in the Japanese mandarin. The sweet and fruity flavor was stronger in the Korean mandarin oil while herbaceous flavor was stronger in Japanese sample. From GC-O data it is suggested that the sweet and fruity flavor of the Korean mandarin resulted from terpinolene and linalool, and the herbaceous note of the Japanese mandarin from $\alpha$-humullene, nepal, ι-carvone and perill aldehyde.