• Preventive Nutrition and Food Science
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• v.14 no.1
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• pp.76-85
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• 2009

This study determined the effect of refrigerated and thermal storage on the volatile profile of commercial aseptic soymilk. Volatile components in commercial aseptic soymilk stored either under refrigerated ($4^{\circ}C$) or thermal ($55^{\circ}C$) conditions for 30 days were periodically analyzed by combined solvent-assisted flavor evaporation-gas chromatography-mass spectrometry (SAFE-GC-MS). The concentrations of most of the volatile components, including aldehydes, ketones, alcohols, acids, nitrogen- and sulfur-containing compounds, alkylfurans, furan derivatives and phenolic compounds, were affected to a greater extent by thermal storage compared with refrigerated storage. Profound increases in some volatile compounds with low odor detection thresholds, such as hexanal, octanal, (E)-2-octenal, (E,E)-2,4-decadienal, 1-octen-3-ol, 3-ethyl-2,5-dimethylpyrazine, 2,3-diethyl-5-methylpyrazine, 2-pentylfuran, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, dimethyl trisulfide, guaiacol, 4-vinylguaiacol and 4-vinylphenol, were observed in thermal stored soymilk. The volatile profile changes caused by thermal storage may influence the aroma quality of thermal-stored aseptic soymilk.

• Toxicological Research
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• v.31 no.3
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• pp.273-278
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• 2015

The aim of this study was to develop an efficient quantitative method for the determination of acetaldehyde (AA) and formaldehyde (FA) contents in solid and liquid food matrices. The determination of those compounds was validated and performed using gas chromatography-mass spectrometry combined by solid phase micro-extraction after derivatization with O-(2,3,4,5,6-pentafluoro-benzyl)-hydroxylamine hydrochloride. Validation was carried out in terms of limit of detection, limit of quantitation, linearity, precision, and recovery. Then their contents were analyzed in various food samples including 15 fruits, 22 milk products, 31 alcohol-free beverages, and 13 alcoholic beverages. The highest contents of AA and FA were determined in a white wine (40,607.02 ng/g) and an instant coffee (1,522.46 ng/g), respectively.

• Toxicological Research
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• v.31 no.3
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• pp.265-271
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• 2015

This study was carried out to investigate contents of 8 polycyclic aromatic hydrocarbons (PAHs) from frequently consumed seafood and dairy products and to evaluate their chemical analysis methods. Samples were collected from markets of 9 cities in Korea chosen as the population reference and evaluated. The methodology involved saponification, extraction with n-hexane, clean-up on Sep-Pak silica cartridges and gas chromatograph-mass spectrometry analysis. Validation proceeded on 2 matrices. Recoveries for 8 PAHs ranged from 86.87 to 103.57%. The limit of detection (LOD) 8 PAHs was $0.04{\sim}0.20{\mu}g/kg$, and limit of quantification (LOQ) of 8 PAHs was $0.12{\sim}0.60{\mu}g/kg$. The mean concentration of benzo[a]pyrene (BaP) was $0.34{\mu}g/kg$ from seafood and $0.34{\mu}g/kg$ from dairy products. The total PAHs concentration was $1.06{\mu}g/kg$ in seafood and $1.52{\mu}g/kg$ in dairy products.

• Journal of Korean Society for Atmospheric Environment
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• v.1 no.1
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• pp.99-107
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• 1985

A coated wire ion selective electrode for nitrate (nitrate-CWE_ was constructed using epoxy resin, ion exchanger and plasticizer as a polymer membrane. It's stility, the composition of a polymer membrane, the response characteristics, the selectivity were examined and applied to the environmental analysis. The nitrate-CWE was prepared using a copper wire, wihch was coated with epoxy resin being incorporated with the nitrate ion exchanger and plasticizer. The best composition of the polymer membrane for the nitrate-CWE was obtained by mixing epoxy resin, ion exchanger and plasticizer in the ratio of 2:1:0.4. The potential (56.3$\pm$0.5 mV) of stick form nitrate-CWE in this composition was close to that (59.2 mV) of Nernstian response. The detection limit for nitrate ion were found to the about $6 \times 10^{-5}M$ and the useful pH was 2.5 $\sim$ 10.3. Furthermore, the selectivity of iodide and perchrorate for the nitrage-CWE was also much improved compared with that for a liquid membrane nitrate electrode. The nitrate-CWE was used to determind $NO_x$ in stack gas. The results were in good agreement with those obtained either by electrode method or by the improved NEDA method within a relative error of 4.0%.

• Environmental Analysis Health and Toxicology
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• v.20 no.4 s.51
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• pp.297-302
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• 2005

The purpose of this study was to provide the standard method for the analysis of organophosphorous pesticides such as chlorpyrifos, diazinon, malathion and parathion in blood. We performed method validation for these pesticides in blood according to EURACHEM (A focus For Analytical Chemistry in Europe) guide. For the analysis of the pesticides, we used solid-phase extraction ,column (Waters Oasis $HLB^{(R)}$. After the extraction, the supernatants were evaporated to dryness under the nitrogen stream. They were analyzed by gas chromatography/mass spectrometry (GC/MS) after reconstituting with ethanol. Terbufos was used as an internal standard. To validate this method, we performed verification procedures with the following parameters: selectivity, linearity of calibration, accuracy, precision, limit of detection and quantification. Validation data according to Eurachem guide were adequate for our purpose for the analysis of chlorpyrifos, diazinon, malathion and parathion in blood.

• Analytical Science and Technology
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• v.15 no.1
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• pp.67-71
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• 2002

The residual analysis and half-life time of imidazole fungicide prochloraz in soils (silty clay) were investigated by gas chromatography equipped electron capture detector (GC-ECD). The soil samples were extracted acetone/hexane(1:1) solvent and analyzed after separated by $LC-NH_2$ Sep-Pak solid column. Linear sensitivity of standard calibration curve was Y = 268.8600X + 0.0664, $R^2=0.9998$ between 0.05~1.00 ng. The detection limit was 0.02 mg/L and the average recoveries were 94.5~97.3% from the standard additional experiments with 0.10 and 0.40 mg/L. The half-life time was 24.4 days in room laboratory and 7.6 days in the field test soil.

• Analytical Science and Technology
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• v.10 no.5
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• pp.332-342
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• 1997

Fifteen volatile organic pollutants were spiked in blank water at the concentration of $20{\mu}g/L$ and analyzed with Purge and Trap and GC/MS. As a result, the overall mean recovery of 100% was obtained with a mean relative standard deviation of 3.6%. The method detection limits were in the range of $1.9{\sim}3.3{\mu}g/L$. In the wastewater analysis of Banwol dyeing comlex, 15 organic compounds were identified and three of these were quantified. Among the compounds identified, only trichloroethylene and tetrachloroethylene are regulated in wastewater by the Korea Ministry of Environment. But, the concentration of these two compounds were below the government allowance level.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 2001.10a
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• pp.140-140
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• 2001

A sensitive analytical method based on gas chromatograpy-mass spectrometry with a selected ion monitoring (GC/MS-SIM) with the purge-and-trap concentration and with headspace method (in limited applications) was developed for determining of epichlorohydrin in canned beverages coated with epoxy resin. The calibration curve in the range of $0.5\sim50ng$ had correlation coefficient greater than 0.998 and a detection limit of $0.l\mug/L$ was obtained using a sample volume of 20ml. The predominant ions of epichlorohydrin produced in MSD using electron ionization(EI) were m/z 57 ([M-CI]+) and 62/64 $([M-CH_2O]+)$. In survey of epichlorohydrin in thirty commercial canned beverage samples, none of them was detected.

• Korean Journal of Head & Neck Oncology
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• v.16 no.2
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• pp.235-237
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• 2000

It is difficult to find the penetrating foreign bodies in the head and neck area only with history taking and physical examinations. One of the most important things is to detect the precise location of foreign bodies or possibly remained materials. The detection of wooden foreign bodies is important because they can cause phlegmon formation and because wood is often contaminated by Clostridium tetani bacteria. CT has proved to be an expedient method for detecting foreign bodies of various materials in soft tissues, but the wooden foreign body is often misinterpreted as a gas bubble in soft tissue. We have experienced a case of wooden foreign body which has penetrated through nasal dorsum and remained for 4 months. It had been initially misinterpreted as longstanding inflammatory lesion and osteitis of maxilla and nasal bone.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.2
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• pp.157-167
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• 2001

Although PAN has ong been considered to belong to one of the most characteristic photooxidants, its concentra-tions have rarely been measured in a systematic manner in Korea. The first in-situ Measurements of PAN were made in concert with simultaneous analysis of NO, NO$_2$, $O_3$ and UV-Visible radiation intensity from Seoul and dong-Hae during Spring and early Summer of 1999. The aim of our study was to evaluate the behavior of photo-chemical species in a highly polluted urban air and a relative clean one. PAN were determined using a semi-auto-mated gas chromatograph equipped with an electron captured detection system. Calibration of the PAN was done by synthesizing liquid standards using a strong acid nitration of the corresponding peracid. The PAN concentra-tions were found in the range of a few ppbv in the urban air ad persistently less than a ppbv in the clean rural airs. Diurnal variations of PAN and $O_3$ were also observed consistently during the experiment with maxima occurring during the late daylight hours. While the positive dependency of $O_3$ production and PAN concentrations were ob-served in most occasion, the dependency became deviated significantly under changes in air masses.