• Korean Journal of Food Science and Technology
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• v.40 no.2
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• pp.123-128
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• 2008

The MRLs (maximum residue limits) of DDT (DDD and DDE) in fresh ginseng, dried ginseng, and steamed red ginseng are set as low as 0.01 mg/kg, 0.05 mg/kg, and 0.05 mg/kg, respectively. Therefore, this study was undertaken to develop a simple and highly sensitive analysis method, as well as to reduce interfering ginseng matrix peaks, for the determination of DDT isomers (o,p'-DDE, p,p'-DDE, o,p'-DDD, p,p'-DDD, o,p'-DDT, and p,p'-DDT) in fresh ginseng, dried ginseng, and steamed red ginseng at the 0.01 mg/kg level. The method used acetonitrile extraction according to simultaneous analysis, followed by normal-phase Florisil solid-phase extraction column clean-up. The purification method entailed the following steps: (1) dissolve the concentrated sample extract in 7 mL hexane; (2) add 3 mL of $H_2SO_4$; (3) vigorously shake on avortex mixer; (4) cetrifuge at 2000 rpm for 5 min; (5) transfer 3.5 mL of the supernatant to the Florisil-SPE (500 mg/6 mL);and (6) elute the SPE column with 1.5 mL of hexane and 10 mL of ether/hexane (6:94). The determination of DDT isomers was carried out by a gas chromatography-electron capture detector (GC-${\mu}$ECD). The hexane and ether/hexane (6:94) eluate significantly removed chromatographic interferences, and the addition of 30% $H_2SO_4$ to the acetonitrile extract effectively reduced many interfering ginseng matrix peaks, to allow for the determination of the DDT isomers at the 0.01 mg/kg level. The recoveries of the 6 fortified (most at 0.01 mg/kg) DDT isomers from fresh ginseng, dried ginseng, and steamed red ginseng ranged from 87.9 to 99.6%. The MDLs (method detection limits) ranged from 0.003 to 0.009 mg/kg. Finally, the application of this method for the determination of DDT isomers is sensitive, rapid, simple, and inexpensive.

• Food Science of Animal Resources
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• v.33 no.5
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• pp.646-654
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• 2013

In this study, quantitative analysis of major volatile flavor compounds from yogurt was conducted using headspace-solid phase microextraction (HS-SPME) GC-FID analysis technique, and the changes of volatile aroma compounds during the storage period were evaluated. The yogurt was prepared with the addition of 2% cereals, such as, white rice (WR), brown rice (BR), germinated brown rice (GBR) and saccharified germinated brown rice (SGBR). After fermentation, the products were stored at $5^{\circ}C$for 15 d. The major volatile aroma compounds in yogurt, such as acetaldehyde, acetone, diacetyl and acetoin were able to be extracted using HS-SPME technique efficiently. The regression ($r^2$) value of standard curve prepared with various concentrations of individual flavor chemicals was analyzed over 0.9975, and reproducibility was acceptable to apply quantitative analysis. The analysis of volatile components of control sample during storage showed that the acetaldehyde on 0 d was 10.83 ppm, and that contents were increased to 15.67 ppm after 15 d of storage. However, addition of BR, GBR and SGBR decreased the acetaldehyde contents during storage periods. The acetone content of all treatments during storage was not significantly different. The diacetyl content of all treatments were increased during storage and the addition of SGBR showed the highest amount of diacetyl (0.84 ppm) among treatments on 15 d of storage. The acetoin content of yogurt added with grains was higher than that of control during storage. As a result, the content of volatile aroma compounds in yoghurt during storage period could be analyzed HS-SPME extraction technique effectively, and HS-SPME/GC analysis can be considered for quality control of fermented milk products.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.3
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• pp.239-254
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• 2015

Little information on HUmic-Like Substances (HULIS) in ambient particulate matter has been reported yet in Korea. HULIS makes up a significant fraction of the water-soluble organic mass in the atmospheric aerosols and influence their water uptake properties. In this study 24-hr $PM_{2.5}$ samples were collected between December 2013 and October 2014 at an urban site in Gwangju and analyzed for organic carbon (OC), elemental carbon (EC), water-soluble OC (WSOC), HULIS, and ionic species, to investigate possible sources and formation processes of HULIS. HULIS was separated using solid phase extraction method and quantified by total organic carbon analyzer. During the study period, HULIS concentration ranged from 0.19 to $5.65{\mu}gC/m^3$ with an average of $1.83{\pm}1.22{\mu}gC/m^3$, accounting for on average 45% of the WSOC (12~ 73%), with higher in cold season than in warm season. Strong correlation of WSOC with HULIS ($R^2=0.91$) indicates their similar chemical characteristics. On the basis of the relationships between HULIS and a variety of chemical species (EC, $K^+$, $NO_3{^-}$, $SO_4{^{2-}}$, and oxalate), it was postulated that HULIS observed during summer and winter were likely attributed to secondary formation and primary emissions from biomass burning (BB) and traffics. Stronger correlation of HULIS with $K^+$, which is a BB tracer, in winter ($R^2=0.81$) than in summer ($R^2=0.66$), suggests more significant contribution of BB emissions in winter to the observed HULIS. It is interesting to note that BB emissions may also have an influence on the HULIS in summer, but further study using levoglucosan that is a unique organic marker of BB emissions is required during summer. Higher correlation between HULIS and oxalate, which is mainly formed through cloud processing and/or photochemical oxidation processes, was found in the summer ($R^2=0.76$) than in the winter ($R^2=0.63$), reflecting a high fraction of secondary organic aerosol in the summer.

• Journal of Environmental Health Sciences
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• v.38 no.2
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• pp.105-117
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• 2012

Objectives: This study aimed to assess the concentration of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) in blood and factors controlling their exposure among Koreans. Methods: Study subjects were selected to include 718 members of the general population residing in five metropolitan cities and the Gangwon Province area from August 2008 to January 2009. A questionnaire was administered to investigate lifestyle, socio-demographic characteristics, and other related factors. Blood samples were collected and extracted using solid-phase extraction and anion-exchange methods, and quantified by high-performance liquid chromatograph (HPLC, Agilent 1200 Series) coupled with a Triple Quad LC-MS/MS system (Agilent 6410). Results: Geometric mean concentrations of PFOA and PFOS in the blood were measured as 1.82 and 6.06 ng/ml, respectively. Mean PFOA and PFOS concentrations generally increased with age in both genders. Blood PFOA concentration was significantly different according to such variables as age, family income, residential district, and province. Blood PFOS concentration was significantly different by such variables as gender, age, lifestyle factors such as regular exercise, alcohol consumption, and smoking status. Also, family income, hazardous facilities, job classification, and province contributed significantly to differences in blood PFOS concentration levels. Conclusions: Blood PFOA and PFOS concentrations in Koreans were similar with those found in Japan, the USA, and Germany, but less than those in Australia. PFOA and PFOS exposure seems to be affected by a variety of factors in Korea. Therefore, investigation is required for each factor to assess the relative contribution of different variables.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.9
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• pp.825-830
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• 2009

Pharmaceutical compounds enter the water environment through the diverse pathways. Because their concentration in the water environment was frequently detected in the level of ppt to ppb, the monitoring system should be optimized as much as possible for finding appropriate management policies and technical solutions. One Factor At a Time (OFAT) approach approximating the response with a single variable has been preferred for the optimization of LC-MS/MS operational conditions. However, it is common that variables in analytical instruments are interdependent. Therefore, the best condition could be found by using the statistical optimization method changing multiple variables at a time. In this research, response surface analysis (RSA) was applied to the LC-MS/MS analysis of emerging antibiotic compound, sulfamethoxazole, for the best sensitivity. In the screening test, fragmentation energy and collision voltage were selected as independent variables. They were changed simultaneously for the statistical optimization and a polynomial equation was fit to the data set. The correlation coefficient, $R^2$ valuerepresented 0.9947 and the error between the predicted and observed value showed only 3.41% at the random condition, fragmentation energy of 60 and collision voltage of 17 eV. Therefore, it was concluded that the model derived by RSA successfully predict the response. The optimal conditions identified by the model were fragmentation energy of 116.6 and collision voltage of 10.9 eV. This RSA can be extensively utilized for optimizing conditions of solid-phase extraction and liquid chromatography.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.12
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• pp.1755-1761
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• 2016

Volatile flavor compounds in soy sauce residue (SSR) and acid hydrolysate of SSR (AHSSR) were analyzed by solid phase micro extraction (SPME)/gas chromatography (GC)/mass spectrometry (MSD) methods. A total of 79 compounds were detected in samples (66 SSR and 60 AHSSR). Quantitatively, alcohols (433.37 ng/g), aldehydes (273.01 ng/g), esters (236.80 ng/g), and aromatic hydrocarbons (180.66 ng/g) were dominant in the volatiles of SSR, whereas furans (249.27 ng/g) were only dominant in AHSSR (P<0.05). Among these, four esters, 3-methylbutyl acetate (banana/pear-like), ethyl 3-methyl butanoate (fruity), ethylbenzene acetate (wine-like), and ethyl 3-methyl butanoate (apple-like), three alcohols, 3-methyl-1-butanol (fruity/whisky-like), 2-phenylethanol (floral/sweet), and 1-octen-3-ol (mushroom-like), four aldehydes, (E)-2-phenyl-2-butenal (chocolate-like), benzaldehyde (almond-like), 3-methylbutanal (malty), and 2-phenylacetaldehyde (floral), four aromatic hydrocarbons, 4-ethyl-2-methoxyphenol (smoky/soy sauce-like), 4-ethylphenol (medicine-like), 4-vinyl-2-methoxyphenol (woody), and phenol (woody), and two furans, furfural (almond-like) and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel-like), were major compounds in SSR, whereas seven compounds, including furfural, 5-methylfurfural (almond-like), 3-methyl-1-butanol, 2-phenylethanol, 4-ethyl-2-methoxyphenol, 3-methylbutanal, and benzaldehyde were major compounds in AHSSR.

• Analytical Science and Technology
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• v.7 no.1
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• pp.33-39
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• 1994

The purpose on this study was to develop a new improved chromatographic method for determination of trace phenols from environmental waste water. The research was carried out with selected 8 phenols, and solid-phase extraction was employed as sample pretreatment method. The coupling of XAD-4 and Dowex $1{\times}8$ resin as preconcentration column increased the selectivities toward interferences coexisted in matrix. Automation was accomplished with on-line process of pretreatment and HPLC system. After elution of sample through XAD-4 column, phenols were adsorbed by dispersion force, then displaced from it by ACN basified, simultaneously and selectively readsorbed via anion exchange on Dowex $1{\times}8$. Dowex $1{\times}8$ column was washed by water. Phenols readsorbed were removed from Dowex $1{\times}8$ column by a minimum volumn of methanol containing HCl. Each pretreatment step was connected by switching valves and the eluate was directly on-line injected to obtain fast and reliable results into the HPLC. Recovery of phenols was greater than 90%. To examine utility of this method, analysis of phenols from laboratory waste water sample which was added some organic pollutants to find with phenols on environmental waste water were also accomplished without their interference effects.

• Journal of Food Hygiene and Safety
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• v.31 no.5
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• pp.319-326
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• 2016

Colistin is a last resort antimicrobial agent against multi-drug resistant Gram-negative bacteria. This study was conducted to develop an analytical method to determine colistin in fish and shrimp. The analytes were confirmed and quantified via liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the positive ion mode using multiple reaction monitoring (MRM). The sample was extracted with acidified 5% methanol (containing 0.5% formic acid). Then, solid phase extraction (SPE) was used for cleanup. Matrix-matched calibration curves were linear over the calibration ranges (0.05-1.2 mg/kg) for all the analytes into blank sample with $r^2$ > 0.99. All the values fulfilled the criteria requested by the Codex guidelines. Average recoveries ranged from 85.9% to 107.9%. The repeatability of measurements, expressed as the coefficient of variation (CV, %), was less than 15%. The limit of detection (LOD) was 0.02 mg/kg, and the limit of quantitation (LOQ) was 0.05 mg/kg. This improved method showed higher accuracy and acceptable sensitivity to meet the CAC guideline requirements and is applicable for the analysis of residual colistin (A+B) in fish and shrimp.

• Korean Journal of Food Science and Technology
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• v.26 no.6
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• pp.750-758
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• 1994

Flavour components of seven Korean folk sojues, five Chinese kaoliangchiews and Japanese shochu were determined by GC and GC-MS after solid phase extraction with polydivinyl benzene. Less volatile ethyl succinate and ethyl pelargonate were present in Korean folk sojues while volatile ethyl acetate and ethyl butyrate in Chinese kaoliangchiews. In the case of alcohols, the amount of isopentyl alcohol was relatively higher than that of isobutyl alcohol or n-propyl alcohol in Korean folk sojues. On the contrary, less volatile n-propyl alcohol was present more than isopentyl alcohol in Chinese kaoliangchiews. Multivariate statistical analyses involving principal components analysis (PCA) and discriminant analysis (DA) were applied to the GC data. The results of PCA clearly demonstrate that the first principal scores of Korean folk sojues were similar but the second principal scores were different from each other. Classification of Korean sojues and Chinese kaoliangchiews into two groups could be conducted by DA. These results suggested that the common charateristics and identities as a distilled liquors was found in Korean folk sojues.

• Korean Journal of Food Science and Technology
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• v.37 no.3
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• pp.339-344
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• 2005

Volatile compounds, isolated from Elsholtzia splendens using simultaneous steam distillation extraction (SDE) and headspace solid phase microextraction (HS-SPME), were analyzed by gas chromatography/mass spectrometry(GC-MS). Twenty-nine compounds, comprising 3 aldehydes, 7 alcohols, 11 hydrocarbons, 5 ketones, and 3 miscellaneous ones, were tentatively identified from volatile compounds of Elsholtzia splendens flowers. From leaves, 30 compounds, comprising 3 aldehydes, 6 alcohols, 11 hydrocarbons, 6 ketones, and 11 miscellaneous ones, were tentatively identified. Volatile compounds extracted by HS-SPME in E. splendens flowers were 3 alcohols, 18 hydrocarbons, 3 ketones, and 2 miscellaneous ones. In leaves, 31 compounds, comprising 7 alcohols, 15 hydrocarbons, 7 ketones, and 2 miscellaneous ones, were tentatively identified. Major volatile compounds identified by SDE and HS-SPME were naginataketone and elsholtziaketone, which were identified as aroma-active compounds, representing characteristic aroma of E. splendens.