• Korean Journal of Environmental Agriculture
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• v.40 no.2
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• pp.134-141
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• 2021

BACKGROUND: The analytical method was established for determination of fungicide chinomethionat in several animal commodities using gas chromatography (GC) coupled with electron capture detector (ECD). METHODS AND RESULTS: In order to verify the applicability, the method was optimized for determining chinomethonat in various livestock products including beef, pork, chicken, milk and egg. Chinomethionat residual was extracted using acetone/dichloromethane(9/1, v/v) with magnesium sulfate and sodium chloride (salting outassociated liquid-liquid extraction). The extract was diluted by direct partitioning into dichloromethane to remove polar co-extractives in the aqueous phase. The extract was finally purified with optimized silica gel 10 g. CONCLUSION: The method limit of quantitation (MLOQ) was 0.02 mg/kg, which was in accordance with the maximum residue level (MRL) of chinomathionate as 0.05 mg/kg in livestock product. Recovery tests were carried out at two levels of concentration (MLOQ, 10 MLOQ) and resulted in good recoveries (84.8~103.0%). Reproducibilities were obtained (Coefficient of variation <5.2%), and the linearity of calibration curves were reasonable (r²>0.995) in the range of 0.01-0.2 ㎍/mL. This established analytical method was fully validated and could be useful for quantification of chinomathionat in animal commodities as official analytical method.

• Analytical Science and Technology
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• v.21 no.6
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• pp.543-552
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• 2008

This paper described the relatively sensitive and simultaneous analytical method for 3-monochloropropane-1,2-diol (3-MCDP, $C_3H_7ClO_2$, MW. 110) as well as 1,3-dichloropropan-2-ol (1,3-DCP, $C_3H_6Cl_2O$, MW. 128) in various foods. Food samples were homogenized in 5M NaCl solution, mixed with aluminum oxide and eluted with dichloromethane. The extracted chloropropanols were concentrated by rotary evaporator and $N_2$ blow serially were derivatized with HFBA (Heptafluorobutyric anhydride, $C_8F_{14}O_3$, MW. 410) and were determined by GC/MS using isotope dilution method. The characteristic molecular ions at m/z 253, 275, 289, 291, and 453 for HFBA derivatives of 3-MCPD (MW. 502) and 110, 275, and 277 for HFBA derivatives of 1,3-DCP (MW. 325) were chosen in selected ion mode. The method validation data showed sufficiently good properties of LOD (0.003 mg/kg), LOQ (0.010 mg/kg), linearity ($R^2{\geq}0.999$ at 0.010~1.000 mg/kg), and recovery rate (${\approx}97%$). The levels of chloropropanols in soy sauce, sauces, processed meat products, fishery products, and seasonings (n=56/157) determined by the presented method were 0.0~0.3 mg/kg.

• Analytical Science and Technology
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• v.21 no.2
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• pp.93-101
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• 2008

The application of solid phase microextraction (SPME) is generally conducted by directly immersing the fiber into the liquid sample or by exposing the fiber in the head space (HS). The extraction temperature, the time of incubation, and application of stirring are often designated to be the most important parameters for achieving the best extraction efficiencies of HS-SPME analysis. In this study, relative importance of these three analytical parameters involved in the HS-SPME method is evaluated using a polydimethylsiloxane/carboxen (PDMS/CAR) fiber. To optimize its operation conditions the competing relationships between different parameters were investigated by comparing the extraction efficiency based on the combination of three parameters and two contracting conditions: (1) heating the sample at 30 vs. 50 C, (2) exposing samples at two durations of 10 vs. 30 min, and (3) application of stirring vs. no stirring. According to our analysis among 8 combination types of HS-SPME method, an extraction condition termed as S50-30 condition ((1) 1200 rpm stirring, (2) $50^{\circ}C$ exposure temp, and (3) 30 min exposure duration) showed maximum recovery rate of 45.5~68.5% relative to an arbitrary reference of direct GC injection. According to this study, the employment of stirring is the most crucial factor to improve extraction efficiency in the application of HS-SPME.

• Journal of Food Hygiene and Safety
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• v.38 no.3
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• pp.89-98
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• 2023

Currently, no guidelines exist regarding the maximum residues of pesticides in edible oil which is a processed food commonly consumed in Korea. This lack of guidelines hinders the evaluation of the safety of edible oil in terms of pesticide contamination. In this study, an analysis method based on heat distillation and GC-MS/MS was established by optimizing the extraction and purification procedure for 68 pesticides. Important variables in the thermal distillation procedure included heating temperature and time, and we found the nitrogen flow rate as a mobile phase and the type of dissolving solvent were not considerably affected. The determination coefficient (R²) of the residual pesticide was 0.99 or higher, and the quantitative limit (LOQ) was 0.01-0.02 mg/L. The average recovery rate (n=5) was 66.1-120.0% and the relative standard deviation was lower than ±10% when 68 pesticides were spiked at concentrations of 0.01-0.02, 0.1, and 0.5 mg/L. In addition, the within-laboratory precision was less than ±11%, meeting the Korea Food and Drug Safety Evaluation Institute's Guidelines on Standard Procedures for Preparing Food Testing Methods (2016). Therefore, the test method developed in this study can be used as a test method for managing the safety of the residual pesticide concentration in edible oil.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1527-1527
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• 2001

Glucose, fructose and sucrose being the main sugars that can be found in natural fruit juice. Many instrumental methods, such as GC, LC, electrochemical or spectrometric methods provide information about both the total content of sugars and the specific concentration of each carbohydrate[1]. The simplicity of sample handling and measurement in the near IR(NIR) wavelength region, which allows the use of long pathlength, optical glass cells and optical fibers, makes NIR a good alternative for sugar determination [2]. In the present study, six varieties of persian grapes were harvested at intervals through august to october and analysed for sugars by NIR. The results were processed by principal component regression (PCR) and partial least squares (PLS) analysis. Sample juice was prepared by squeezing through gauze from crashed grape. This solution was treated by zinc ferrocyanide prior to analysis in order to eliminate colored compounds and all optically active nonsugar substances. For glucose and fructose the most characteristic wavelengths were 1456nm corresponding to the first harmonic O-H stretching and the second at 2062nm corresponding to O-H stretching and deformation; secondary characteristic combination bands were also seen at 2265 nm (O-H and C-C stretching) and at 2240 nm (C-H and C-C stretching). However these spectra were taken over a wavelength range from 1100-2500nm at room temperature of 25-$30^{\circ}C$. To test the accuracy of the described procedure, samples of six varieties of grape were analysed by the proposed NIR and a standard method[2]. Good agreement were found between these two sets of the results. To perform the recovery studies , samples of grape juices previously analysed by the proposed method, were spiked with known amounts of each individual sugars and then analysed again. Relative standard deviations varied from 1.4 to 1.8% for six independent measurements of individual and total sugar concentration. In the analysis of real and synthetic samples, precise and accurate results were obtained , providing accuracy errors lower than 1.9% in all cases. Average recoveries of ${97}{\pm}{4%}$ for total sugar and between ${95}{\pm}{5%}$ and ${99}{\pm}{2%}$ for sing1e sugars demonstrate the applicability of the methodology developed to the direct analysis of grape Juice.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.5
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• pp.547-556
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• 2007

The release, sampling and analytical methods have been developed and tested for perfluorocarbons (PFCs) atmospheric tracers in order to gain insight into the atmospheric transport and dispersion over the urban conditions of Seoul, Korea. Although PFCs tracer experiments provide unique opportunities to test local and urban scale of transport and dispersion, no previous experiment with PFCs has been conducted in Korea. PMCH and PDCH were chosen as targeted tracers in our study due to their extreme low ambient concentrations and great sensitivities among various PFCs. For PFCs release system, a set of micro-metering pump, electronic balance, vaporizing furnace and high speed blower was constructed for precise and accurate release of tracers. The precision of released rate by this system was estimated to be 1%. Samplings of PFCs were carried out by fabricated portable air samplers with micro pumps and rotameters into glass tubes packed with 150 mg of Carboxen-569. The uncertainty of these sampling system was maintained below 14%. PMCH and PDCH were quantified in GC/ECD with preconditioned injection system to eliminate the interference compounds using traps and subsequent catalytic conversion system prior to column separation. Three intensive field test were undertaken during the springtime of 2002 to 2004 in eastern part of Seoul. Daily background samples were collected to characterize the background levels of PMCH and PDCH prior to their release. The observed background concentrations of PMCH ranged from 3.5 to 10.1 fL/L and varied randomly in location and time in this study. Its mean and standard variation of background concentration ($6.8{\pm}1.9\;fL/L$) are higher than those ($3.2{\sim}5.8\;fL/L$) of other historic tracer studies. Identified uncertainty for background PMCH was $1.7{\sim}2.0\;fL/L$ using this analytical system. Combined relative uncertainty in determining the tracer's concentrations was estimated as 17%. However, its background concentrations and uncertainty in concentration determination were found to be low and stable enough for tracer study.

• Journal of Soil and Groundwater Environment
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• v.17 no.4
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• pp.63-72
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• 2012

The main objective of this study is to assess the compatibility between Korean ministry of environment (KME) standard and ISO (KS I ISO) standard for the determination of BTEX and TPH content in soil. We carried out comparison analysis for both methods using CRM and matrix spiked samples. In case of GC-MS analysis for BTEX, we got statistically (significance level: 0.05) the same results from KME standard (ES 07600.1) and ISO standard (KS I ISO 15009). However, it showed statistically (significance level: 0.05) different results when TPH was analyzed by KME standard (ES 07552.1) and ISO standard (KS I ISO 16703). To clarify the reason why both methods produced different results for TPH content, we also did some additional experiments in terms of differences in extraction, clean-up and target hydrocarbon range. Extraction with polar and non-polar compounds mixed solvent (acetone+n-heptane) of KS I ISO 16703 showed higher extraction efficiency than with only non polar solvent (dichloromethane) extraction of ES 07552.1 by about 9%. While column type clean-up of KS I ISO 16703 showed the reduction in TPH content between before and after clean-up, batch type of clean-up of ES 07552.1 did not show any changes in TPH content through clean-up process. The target hydrocarbon range of ES 07552.1 and KS I ISO 16703 is $C_8{\sim}C_{40}$ and $C_{10}{\sim}C_{40}$, respectively. From this point of view, kerosene and JP-8 contaminated soil showed higher RPD (relative producibility deviation) values between results by both method than that of lubricant or diesel contaminated soil. The higher content of hydrocarbon ($C_8{\sim}C_{10}$) in kerosene and JP-8 played an important role in increasing RPD values in addition to the effects caused by different solvents and clean-up method. Consequently, it was concluded that both methods (ES 07552.1 and KS I ISO 16703) were not compatible.

• Korean Journal of Clinical Laboratory Science
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• v.37 no.1
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• pp.22-26
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• 2005

Total homocysteine is now considered a risk factor for cardiovascular diseases. I increased interest has led to a multitude of studies requiring the determination of total homocysteine in conjunction with other factor. There are various methods for measuring total homocysteine, including HPLC, FPIA, GC-MS and LC-MS/MS. The most recent method for measuring total homocysteine uses a deuterium-labelled internal standard and tandem mass spectrometry. This development requires no derivatization and therefore leads to an increase in sample throughput compared to other techniques. We have evaluated the method for homocysteine by the LC-MS/MS method, and the correlation between the FPIA method and the LC-MS/MS method. The standard curve (0, 5, 10, 20, 50, 100 uM) was linear over the range examined (up to 100 uM). The lower limit of quantification (CV < 10 %) was 0.5 uM/L and the lower limit of detection (S/N >3) was 0.1 uM/L. Intra-assay variation and inter-assay variation were both <6 %. The comparision study for homocysteine concentration showed good correlation (r=0.9684) between the FPIA method and LC-MS/MS methods. Our conclusion is that the method showed relatively good precision, and was rapid and accurate.

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.684-688
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• 2010

Biodiesel produced from the reaction of methanol and triglyceride which is the main component of animal fats and vegetable oils is known for remarkable lubricity. In this study, the lubricity of 3 kinds of biodiesel came from vegetable oils such as soybean oil, palm oil, and perilla oil and 2 kind of biodiesel which were produced from beef tallow and pork lard were analyzed using HFRR (High frequency reciprocating rig). In HFRR test result, the lubricity of perilla and soybean's biodiesel was higher than other biodiesels. After analysis of biodiesel components by GC-MS and determination of the lubricity of pure biodiesel components using HFRR, it was found that a higher olefin content and long alkyl chaining biodiesel had an excellent lubricity property.

• 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.