• The Korean Journal of Pesticide Science
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• v.8 no.1
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• pp.46-53
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• 2004

Adsorption and leaching characteristics of hexaconazole were investigated to estimate the mobility potential of the compound in the soil environment. As well fitted to Freundlich adsorption isotherm, adsorptivity of hexaconazole, ranged 10.56-18.01 of Kf values, seemed high enough to be immobile in soil. This chemical leached more faster from fresh soil with rice plants. Most of $^{14}C$ (86-99% of originally applied $^{14}C$) was distributed within 5 cm soil depth from surface. Considering Koc values of 1,400-1,552 and Groundwater Ubiquity Score (GUS) indices of 1.25-1.35 as well as results from leaching experiment with soil column, hexaconazole falls into the category of improbable leacher, suggesting little mobility in soil.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.258-268
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• 2014

The test method of aerobic transformation in soil has established based on international test guideline (OECD TG 307). And then, the case study was conducted with [$^{14}C$]butachlor. Butachlor is commonly used herbicide in Korea. [$^{14}C$]Butachlor was treatrd $6.83mgKg^{-1}$ in loamy soil. The treated soil was incubated in flow-through system for 60 days. The mass balance of applied radioactivity (AR) ranged from 91.1 to 95.5% and from 93.0% to 97.7% for non-sterile and sterile soils, respectively. In non-sterile soil, the concentration of [$^{14}C$]butachlor was declined from 94.4% AR at 0 day to 8.4% AR at 60 days after treatment. 2-Chloro-2',6'-diethylacetanilide was the major degradation product detected in soil extract. The calculated $DT_{50}$ and $DT_{90}$ of butachlor were 10.4 days and 34.6 days, respectively. $^{14}CO_2$ and non-extractable soil residue were increased up to 3.5% and 43.5% AR at 60 DAT. There is no significant decrease of the [$^{14}C$]butachlor through the incubation period in sterile soil.

• The Korean Journal of Pesticide Science
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• v.17 no.2
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• pp.107-116
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• 2013

Polar pesticides like pymetrozine (log $P_{ow}$: -0.18) are known to be difficult to analyze. The analytical method of pymetrozine using hydromatrix included in the official method of KFDA was uncommon and provided ambiguous evidence to confirm both the identity and the quantity. Therefore, precise single residue analytical method was developed in representative crops for using liquid-liquid extraction (LLE). The pymetrozine residue was extracted with methanol from 11 representative crops which comprised apple, blueberry, broccoli, cabbage, cherry, crown daisy, hulled rice, Korean cabbage, potato, rice and watermelon. The extract was purified serially by liquid-liquid extraction (LLE) and silica solid phase extraction (SPE). For rice and hulled rice samples, n-hexane partition was additionally adopted to remove nonpolar interferences, mainly lipids. The residue levels were analyzed by HPLC with DAD, using $C_8$ column. LOQ (limit of quantitation) of pymetroizinie was 1 ng (S/N > 10) and MQL (method quantitation limit) was 0.01 mg/kg. Mean recoveries from 11 crop samples fortified at three levels (MQL, 10 ${\times}$ MQL and 50 ${\times}$ MQL) in triplicate were in the range of 83.1~98.5% with coefficients of variation (CV) of less than 10%, regardless of sample type, which satisfies the criteria of KFDA. The method established in this study could be applied to most of crops as an official and general method for analysis of pymetrozine residue.

• The Korean Journal of Pesticide Science
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• v.15 no.2
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• pp.125-133
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• 2011

Ametryn is used in USA, China, and Japan, but not introduced in Korea yet. So, MRL (Maximum Residue Level), and analytical method of ametryn were not establishment in Korea. Therefore, this experiment was conducted to establish a determination method for ametryn residue in crops using HPLC-UVD/MS. Ametryn residue was extracted with acetone from representative samples of five raw products which comprised hulled rice, soybean, apple, green pepper, and Chinese cabbage. The extract was diluted with saline water, and dichloromethane partition was followed to recover ametryn from the aqueous phase. Florisil column chromatography was additionally employed for final clean up of the extract. The ametryn was quantitated by HPLC with UVD, using a Tosoh ODS 120T ($4.6{\times}250$ mm) column. The crops were fortified with ametryn at 2 levels per crop. Mean recovery ratio were ranged from 83.7% for a 0.2 mg/kg in soybean to 91.1% for a 1.0 mg/kg in hulled rice. The coefficients of variation were ranged from 1.2% for a 1.0 mg/kg in hulled rice to 3.6% for a 1.0 mg/kg in soybean. Quantitative limit of amatryn was 0.02 mg/kg in representative 5 crop samples. A LC/MS with selected-ion monitoring was also provided to confirm the suspected residue. Therefore, this analytical method was reproducible and sensitive enough to determine the residue of ametryne in agricultural commodities.

• The Korean Journal of Pesticide Science
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• v.3 no.1
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• pp.57-65
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• 1999

The midge Chironomus riparius is a member of widespread dipteran insect which has been used for sediment toxicity test. The 2nd-3rd larvae Chironomus riparius were exposed to $^{14}C$-lambda-cyhalothrin in laboratory water only system(A) and sediment-water system(B) at $20{\pm}2^{\circ}C$. The concentration was nominally in the range of 0.16 to $20{\mu}g/{\ell}$ and 62.5 to 8000 ${\mu}g/kg$, respectively. System(A) was prepared by applying the chemical to 250 ml water and introducing Chironomus riparius larvae into the system(day 0). System(B) was prepared by applying the chemical to the 25 g of soil and 250 ml water and shaking and rolling them for two hours. After allowing the system to settle for two days, Chironomus riparius larvae were introduced into the system. After 72 hours, the two systems were terminated and dead larvae were observed. The measurement of residue in water was conducted at the start(day 0) and the end of the study(day 3). The residue of $^{14}C$-lambda-cyhalothrin in water was accounted for approximately 65% of nominal concentration in system(A) and $0.2{\sim}0.4%$ in system) on 3 days. $LC_{50}$ was less than $0.156{\mu}g/{\ell}$ in system(A) and 889 ${\mu}g/kg$ in system(B), based on the nominally applied concentration.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.389-400
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• 2011

A high-performance liquid chromatographic (HPLC) method was developed to determine residues of phenothrin and silafluofen, known as synthetic pyrethroids, in agricultural commodities. Insecticide residues were extracted with acetone from representative samples of four crops which comprised rice, apple, pepper and cabbage. The extract was purified serially by liquid-liquid partition and Florisil column chromatography. For rice and pepper samples, acetonitrile/n-hexane partition was additionally adopted to remove nonpolar interferences. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate two phenothrin isomers and silafluofen from sample co-extractives. Intact parent compounds were sensitively detected by ultraviolet absorption at 226 nm. Recovery experiment at the quantitation limit validated that the proposed method could apparently determine phenothrin and silafluofen residues at 0.02 and 0.01 mg/kg, respectively. Mean recoveries of phenothrin and silafluofen from four crop samples fortified at three levels in triplicate were in the range of 82.4~109.8% and 83.7~109.8%, respectively. Relative standard deviations of the analytical method were all less than 10%, irrespective of crop types and spiking levels. A selected-ion monitoring (SIM) LC/mass spectrometry (MS) with electrospray ionization was provided to confirm the suspected residue of phenothrin, even though no sufficient ionization of silafluofen was obtained. Both phenothrin and silafluofen could be successfully confirmed by gas chromatography/MS SIM with electron impact at 70 eV. The proposed method is sensitive, repeatable and rapid enough to apply to officially routine inspection of agricultural products.

• Journal of Environmental Science International
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• v.8 no.3
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• pp.379-386
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• 1999

The adsorption and leaching of organophosphorus pesticides (phenthoate, diazinon, methidathion) were investigated in Namwon soli(black volcanic soil), Aewol soil(very dark brown volcanic soil) and Mureung soil(dark brown nonvolcanic soil) sampled in Cheju Island. The Freundlich constant, K value, was 52.4, 31.3 and 27.7 for phenthoate, diazinon and methidathion in Namwonsoil, respectively and decreased in the order of phenthoate, diazinon and methidathion among the pesticides. The K value of phenthoate was 52.4, 15.9 and 5.9 for Namwon, Aewol and Mureung soil, respectively and was the highest for Namwon soil with very high organic matter content and cation exchange capacity(CEC). The Freundlich constant, 1/n, showed a high correlation with organic matter content, i.e., its value was less than unity for organic matter rich soil(Namwon soil) and greater than unity for organic matter poor soil(Mureung soil). Total recoveries of pesticides in soil and leachate with leaching in soil column, were in the range of about 74~86%. The leaching of pesticides was less for phenthate with high K values, and more for methidathion with low K values among the pesticides. It was slower for Namwon soil with high K values, and more for methidathion with low K values among the pesticides. It was slower for Namwon soil with high K values, and faster for Mureung soil with low K values among the soils.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.125-130
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• 2004

This study has been assessed the influence of applying sewage sludge to soil amendments on the sorption properties, and leaching potential of three commonly used organophosphorus pesticides, Diazinon, Fenitrothion, and Chlorpyrifos. A sandy soil with a low content of organic carbon was treated with sewage sludge with a ratio sandy soil : sludge ratio of 30:1. The sorption was determined with the batch equilibrium technique. The sorption isotherms could be described by Freundlich equation. The Freundlich constant, K value which measures sorption capacity, were 3.97, 9.94, 22.48 for Diazinon, Fenitrothion, Chlorpyrifos in non-amended soil. But in amended soil, K value was 12.58, 28.47, and 61.21 for Diazinon, Fenitrothion, and Chlorpyrifos. The overall effect of sewage sludge addition to soil was to increase pesticides adsorption, due to the high sorption capacity of the organic matter. The effect of sludge on tile leaching of pesticides in the soil was studied using packed soil columns. Total recoveries of pesticides in soil and leachate with leaching in soil column, were in the range of about 73～84%, was reduced with the passage of time. Diazinon moved more rapidly than Chlorpyrifos in the unamended soil due to greater sorption and lower water solubility of Chlorpyrifos. Total amounts of pesticides leached from the sewage sludge amended soils were significantly reduced when compared with unamended soils. This reduction may be mainly due to and increase in sorption in amended soils, as a consequence of the increase in the organic matter content.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.173-177
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• 2006

Pesticides from diffuse pollution sources adsorbed in suspended particles flow into surface water and threats to the public health. In this research, dechlorination constants of Atrazine by zero valent iron were measured with addition of buffer solution for simulating buffer capacity of sediment. When initial concentration of Atrazine was 10, 30, and 50 mg/L, their dechlorination was explained using the pseudo-first order reaction. Dechlorination constants $K_{obs}$ were $3.21{\times}10^{-2}/d$ in average.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.7-10
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• 2001

Adsorption of the pesticides (phosphamidon, fenitrothion, triadimefon and diniconazole) in natural zeolite (CL $I_{N}$) and several synthetic zeolites was incestigated. The pesticides were not adsorbed on zeolites (Na-Pl, SOD, ANA, JBW and CAN) synthesized from Jeju scoria. The distribution coefficient ( $K_{D}$) and the Freundlich constant ( $K_{F}$) decreased in the following sequences. FC $C_{W}$ (waste catalytic cracking catalyst)>FA $U_{F}$ (FAU Synthesized from coal fly ash)>(FAU+Na-Pl)$_{SF}$ (the mixture of FAU and Na-Pl synthesized from the ratio of Jeju scoria 6 to coal fly ash 4 by weight)>CL $I_{N}$ among the zeolites; diniconazole>fenitrothion> triadimefon>phosphamidon. As the temperature was increased, the amount of pesticide adsorbed per unit mass of zeolite increased for FC $C_{W}$, FA $U_{F}$ and (FAU+Na-Pl)$_{SF}$ but it decreased for CL $I_{N}$, for all the pesticides used in this study. It was independent of pH for phosphamidon, fenitrothion and triadimefon, but decresed as pH was increased for all the zeolites used in this study.y.udy.y.y.y.y.y.y.