• The Korean Journal of Pesticide Science
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• v.14 no.4
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• pp.347-360
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• 2010

In order to develop the multi-residue purification method for 180 pesticides commonly used in Korea, many analytical methods on individual and multi- pesticide residues in the agricultural commodities and food product were examined. Through the modification of adsorption chromatographic methods used in Europe, the United States and Korea, the Florisil and silica-gel chromatographic systems were developed. Through these purification systems, elution profiles for all pesticides were examined. As the results, 145 pesticides were recovered in the range of 70-120% in Florisil clean-up system. The distribution of pesticides in the elution profile was 12 pesticides in the first fraction, 76 pesticides in the second fraction, 81 pesticides in the third fraction, 60 pesticides in the fourth fraction and 30 pesticides in the last fraction. And, in silica-gel system, 137 pesticides were recovered in the range of 70~120%. The distribution of pesticides in the elution profile was 22 pesticides in the first fraction, 59 pesticides in the second fraction, 102 pesticides in the third fraction, 46 pesticides in the fourth fraction and 8 pesticides in the last fraction.

• The Korean Journal of Pesticide Science
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• v.14 no.4
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• pp.361-370
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• 2010

Considering the efficiencies of the preparation process at each stage obtained in previous studies, the analytical determination method was established for multi-pesticide residues in soils. It consist of the acetone-extraction, the dichloromethane-partition, the Florisil or silica-gel chromatography and the gas chromatography analysis equipped with the electron capture detector and the nitrogen-phosphorus detector. In the soil recovery test by Florisil clean-up system, the number of pesticides recovered in the range of 70~120% and showed less than 20% of RSD were 165 pesticides for paddy soil, 169 pesticides for upland soil and 159 pesticides in both soils through the tested 183 pesticides. And in the soil recovery test by silica-gel system, the number of pesticides recovered in the range of 70~120% and showed less than 20% of RSD were 154 pesticides for paddy soil, 145 pesticides for upland soil, and 134 pesticides in both soils.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.60-67
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• 2011

BACKGROUND: Because dried herbal medicines have many active ingredients, it is not easy to determine the residue amount after extraction, partition and clean up of pesticides from them. Especially, liquid-liquid partition method is consuming many times and solvents. Macroporous diatomaceous earth(MDE) column was used to replace the separatory funnel for liquid-liquid extraction with dichloromethane to analyze the endosulfan and its metabolite. METHODS AND RESULTS: The residue analysis method using MDE column instead of liquid-liquid partition for determining insecticide endosulfan and its metabolite in 4 dried herbal medicines was developed by GC/MS. As a result, the recovery rates of the pesticides in 4 herbal medicines were ranged from 80.3 to 93.5% for ${\alpha}$-endosulfan, from 81.0 to 100.3% for ${\beta}$-endosulfan and from 80.6 to 95.6% for endosulfan sulfate, respectively. The coefficients of variation for triplicate were ranged from 1.1 to 3.4%. CONCLUSION: The improved methods are more ecofriendly, safer, faster and less laborious than conventional method by KFDA.

• Korean Journal of Food Science and Technology
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• v.43 no.2
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• pp.224-229
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• 2011

Zearalenone (ZEA) is an estrogenic mycotoxin mainly produced by Fusarium graminerum, a species which colonizes a wide variety of cereals, including wheat, barley and processed products. A survey of ZEA contamination was conducted on 141 dried confectioneries, 59 breads and rice cakes, 135 noodles and 101 other products, for a total of 432 commercial samples. Samples were analyzed by high performance liquid chromatography with fluorescence detection (HPLC-FLD) after immunoaffinity clean-up and was confirmed by liquid chromatography tandem mass spectrometry (LCMS/MS). The limits of detection and quantification were 2.0 and $6.0{\mu}g/kg$, respectively. The recovery ranged from 80.2% to 98.4% in the cereal based product. ZEA was detected in 38 samples (8.8% incidence), including 3 snack, 2 biscuit and 33 other cereal products. The ZEA contamination levels were in the range of $5.38-53.76{\mu}g/kg$. Finally, LC-MS/MS analysis of the contaminated samples was conducted to confirm the detected ZEA, and all 38 samples showing ZEA by HPLC-FLD were confirmed by LC-MS/MS.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.179-191
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• 2016

In addition to the measurement of the concentration of soil contaminants, the new idea of indicative parameters was proposed to validate the remedial works through the monitoring for the changes of soil characteristics after applying the clean up technologies. The parameters like CFU (colony forming unit), pH and soil texture were recommended as indicative parameters for land farming. In case of soil washing, water content and the particle size distribution of the sludge were recommended as indicative parameters. The sludge is produced through the particle separation process in soil washing and it is usually treated as a waste. The parameters like water content, organic matter content, CEC (cation exchange capacity) and CFU were recommended as indicative parameters for the low temperature thermal desorption method. Besides the indicative parameter, sampling methods in stock pile and the optimal minimum amount of composite soil sample were proposed. The rates of sampling error in regular grid, zigzag, four bearing, random grid methods were 17.3%, 17.6%, 17.2% and 16.5% respectively. The random grid method showed the minimum sampling error among the 4 kinds of sampling methods although the differences in sampling errors were very little. Therefore the random grid method was recommended as an appropriate sampling method in stock pile. It was not possible to propose a value of optimal minimum amount of composite soil sample based on the real analytical data due to the dynamic variation of $CV_{fund{\cdot}error}$. Instead of this, 355 g of soil was recommended for the optimal minimum amount of composite soil sample under the assumption of ISO 10381-8.

• Asian Journal of Atmospheric Environment
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• v.5 no.3
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• pp.146-151
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• 2011

1-Nitropyrene (1-NP), 2-NP and 2-nitrofluoranthene (2-NFR) are useful markers for studying the atmospheric behaviors of polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs). However, present methods for measuring trace levels of these compounds are lesssensitive and laborious. Here we describe several improvements to a previously reported high-performance liquid chromatography-chemiluminescence detection system that allows it to determine trace levels of 1-, 2-NPs and 2-NFR. The proposed system was equipped with a reducer column packed with Pt/Rh instead of zinc whose life-time was limited. The combination of Cosmosil MS-II (monomeric ODS) and AR-II (polymeric ODS) columns was used instead of polymeric ODS columns as the separator column to improve the separation. An ethanol mixture with acetate buffer (pH 5.5) was used in place of an acetonitrile mixture with the same buffer to activate the reducer column. The same ethanol mixture was used as the mobile phase for the clean-up column. The switching time of the column switching valve was optimized to concentrate the amino-derivatives of above NPAHs quantitatively on the concentrator column. The concentrations of bis(2,4,6-trichlorophenly) oxalate and hydrogen peroxide in the chemiluminescence reagent solution were optimized to 0.4 mM and 30 mM, respectively, to increase the sensitivity. Under the above conditions, the detection limits (S/N=3) of 1-, 2-NPs and 2-NFR were 1 fmol (0.25 pg), 10 fmol (2.5 pg) and 4 fmol (1 pg), respectively. The proposed system was effectively used to determine trace levels of 1-, 2-NPs and 2-NFR in airborne particulates collected at Noto Peninsula. The atmospheric concentrations of 1-, 2-NPs and 2-NFR were not more than sub pg $m^{-3}$ levels. They were higher in winter (January) than in summer (July). In both seasons, the concentrations were in decreasing order, [2-NFR]>[1-NP]>[2-NP].

• Korean Journal of Environmental Agriculture
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• v.13 no.2
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• pp.199-208
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• 1994

Analytical methods for the determination of the derivatives of the herbicide (${\pm}$)-2-(4-chloro-2-methylphenoxy)propionic acid (MCPP) by capillary column gas chromatography with mass spectrometer (GC-MS) and electron-capture detection (GC-ECD) were studied. A successful procedure was introduced for the ester preparation using $H_2SO_4$, as the catalyst and the alcohol 2,2,2-trichloroethanol (TCE) or 2,2,2-trifluoroethanol (TFE). The identificaiton and elucidation of MCPP by GC-MS spectrometry following the esterification with diazomethane, $BF_3$/methanol, $H_2SO_4$/methanol, TCE, TFE, or pentafluorobenzyl bromide (PFB) were carried out. A comparison of the response-sensitivities among those MCPP esters was made with GC-ECD. Although the methylation product of MCPP was confirmed by GC-MS, its low sensitivity to the ECD limited the detection of MCPP. TCE, TFE, and PFB derivatization methods resulted in a high rate of MCPP esterifications and very sensitive ECD molecular responses. Based on efficiency, convenience, worker safety, and least sample contamination, TFE esterificaiton was considered as the superior method for MCPP analysis to the other methods of derivatization. An accurate method is described for quantifying MCPP in soil leachates by GC-ECD at very low concentrations without the requirement of a complicated clean-up process. As a result, MCPP residues at concentrations of less than $0.1{\mu}g$ in 100ml soil leachate were detected.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.4
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• pp.227-231
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• 2008

The purpose of this study is to clarify the behavior of stranded crude oil and to estimate the restoration of seawater infiltration by application of dispersant as one of cleaning techniques. We made visualization of infiltration process of seawater and stranded crude oil on the sandy beach sediments by using of a model sandy beach. Major conclusions derived from this study are as follows. The seawater infiltration volume was reduced by the stranded crude oil. However, thirty percentage of the sweater infiltration into the sediments was restored by dispersant application to the penetrated oil in sandy beach. The penetration depth of stranded oil were dropped at first falling tide, but were not significantly fluctuated after that. Moreover, oil concentration was most high within the upper 2 cm. The stranded crude oil was broken into small size droplets and dispersed into the sediments by the dispersant application. Therefore, dispersant applications play an important roles in the large increase of surface area of given volume of oil, and it resulted in promoting to biological degradation process at the oil/water interface, dispersing the stranded oil into the water column and restoration of the supplement of the dissolved oxygen and nutrients to the benthic organisms.

• The Korean Journal of Pesticide Science
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• v.19 no.4
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• pp.345-353
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• 2015

The aim of this study is to develop residue analysis method for fenoxanil, a MBI (melanin biosynthesis inhibitor) propionamide fungicide, had mainly been used to control rice blast, and disease of other crops, fruits, and vegetables by using GLC/NPD and GC/MS. Extraction with acetone and partition with n-hexane/dichloromethane (80/20, v/v) were performed from hulled rice, soybean, Kimchi cabbage, green pepper, and apple, then column clean-up with florisil was applied. Mean recoveries were 82.2%-109.1% with less than 7.2% of coefficients of variation and limit of quantitation was set at the concentration of 0.04 mg/kg from the five agricultural products through the determination by GLC/NPD equipped with DB-5 capillary column and single laboratory validation. As a confirmatory method, GC/MS selected ion monitoring (SIM) was set from m/z 125.0, 188.9, and 293.0. Developed method is expected to apply the single residue analysis of fenoxanil in agricultural products.

• The Korean Journal of Pesticide Science
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• v.19 no.4
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• pp.361-369
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• 2015

This study investigated residual characteristics of bistrifluron and fluopicolide in Korean cabbage, and suggested the pre-harvest residue limits (PHRLs) based on their dissipation patterns and biological half-lives. The pesticides were sprayed on Korean cabbage in two different region under greenhouse conditions at the recommended dose, respectively. The samples for residue analysis were harvested at 0 (2 hr), 1, 2, 4, 6, 8 and 10 days after treatment, and analyzed by HPLC after clean-up with Florisil SPE. The limit of quantification (LOQ) was $0.03mg\;kg^{-1}$ for bistrifluron and fluopicolide, and the recoveries ranged from 87.2-110.6% with below 5% of RSD. The biological half-lives of field I and field II were 3.9 and 4.2 days for bistrifluron and 4.9 and 4.2 days for fluopicolide, respectively. The PHRL of bistrifluron and fluopicolide were recommended as 3.83 and $3.23mg\;kg^{-1}$ for 10 days before harvest, respectively.