• The Korean Journal of Pesticide Science
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• v.13 no.1
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• pp.1-12
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• 2009

To assess the effect of butachlor on freshwater aquatic organisms, acute toxicity studies for algae, invertebrate and fishes were conducted. The algae grow inhibition studies were carried out to determine the growth inhibition effects of butachlor (Tech. 93.4%) in Pseudokirchneriella subcapitata (formerly knows as Selenastrum capriconutum), Desmodesmus subspicatus (formerly known as Scendusmus subspicatus), and Chlorella vulgaris during the exposure period of 72 hours. The toxicological responses of P. subcapitata, D. subspicatus, and C. vulgaris to butachlor, expressed in individual $ErC_{50}$ values were 0.002, 0.019, and $10.4mgL^{-1}$, respectively and NOEC values were 0.0008, 0.0016, and $5.34mg\;L^{-1}$, respectively. P. subcapitata was more sensitive than any other algae species. Butachlor has very high toxicity to the algae, such as P. subcapitata and D. subspicatu. In the acute immobilisation test for Daphnia magna, the 24 and $48h-EC_{50}$ values were 2.55 and $1.50mg\;L^{-1}$, respectively. As the results of the acute toxicity test on Cyprinus carpio, Oryzias latipes and Misgurnus anguillicaudatus, the $96h-LC_{50}s$ were 0.62, 0.41 and $0.24mg\;L^{-1}$, respectively. The following ecological risk assessment of butachlor was performed on the basis of the toxicological data of algae, invertebrate and fish and exposure concentrations in rice paddy, drain and river. When a butachlor formulation is applied in rice paddy field according to label recommendation, the measured concentration of butachlor in paddy water was $0.41mg\;L^{-1}$ and the predicted environmental concentration (PEC) of butachlor in drain water was $0.03 mg\;L^{-1}$. Residues of butachlor detected in major rivers between 1997 and 1998 were ranged from $0.0004mg\;L^{-1}$ to $0.0029mg\;L^{-1}$. Toxicity exposure ratios (TERs) of algae in rice paddy, drain and river were 0.004, 0.05 and 0.36, respectively and indicated that butachlor has a risk to algae in rice paddy, drain and river. On the other hand, TERs of invertebrate in rice paddy, drain and river were 3.6, 50 and 357, respectively, well above 2, indicating no risk to invertebrate. TERs of fish in rice paddy, drain and river were 0.58, 8 and 57, respectively. The TERs for fish indicated that butachlor poses a risk to fish in rice paddy but has no risk to fish in agricultural drain and river. In conclusion, butachlor has a minimal risk to algae in agricultural drain and river exposed from rice drainage but has no risk to invertebrate and fish.

• The Korean Journal of Pesticide Science
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• v.6 no.3
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• pp.218-223
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• 2002

The rate of hydrolysis of insecticide, O,O-diethyl-O-(1-phenyl-3-trifluoromethylpyrazol-5-yl)phosphorothioate (Flupyrazofos) have been investigated in 25% (v/v) aqueous dioxane (${\mu}=0.1M$) at $45^{\circ}C$. The hydrolysis mechanism of flupyrazofos proceeds through the specific acid ($A_{AC}2$) catalysis below pH 4.0, specific base ($B_{AC}2$) catalysis above pH 11.0 and general acid & base ($B_{AC}2$) catalysis between pH 5.0 and pH 10.0 via trigonal-bipyramidal ($d^2sp^3$) intermediate as evidence by solvent effect ($|m|{\ll}|{\ell}|$), rate equation ($kt=ko+k_H+ [H_3O^+]+k_{OH}[OH^-]$) and product analysis. The half-life ($T\frac{1}{2}$) of hydrolytic degradation in neutral media at $45^{\circ}C$ was ca. 3 months.

• Korean journal of applied entomology
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• v.21 no.2 s.51
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• pp.87-94
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• 1982

The mymarids egg parasite of rice planthopper, Anagrus nr. flaveolus, were investigated to know their parasitic activities after overwitering in the paddy banks and barley fields, their host preferences and seasonal variations in the pesticide sprayed and unsprayed paddy fields of Gyeongnam province O.R.D. at Jinju from 1977 to 1979. The parasitic activities of Anagrus nr. flaveolus after overwintering in the paddy banks were high early in April and tended to decrease remarkably since mid-April by moving to the barley fields. The parasitic rate of Anagrus nr. flavelous was $47.2\~88\%$ between middle and late in April, the peak of egg deposition period. Anagrus nr. flaveolus parasitized Laodelphax striatellus, Nilaparvata lugens, and Sogatella furcifera, but didn't attack the eggs of Nephotettix cincticeps in the paddy fields. High preference was observed with Laodelphax steriatellus. The parasitic activities of Anagrus nr. flaveolus in the pesticide sprayed paddy fields were high in early July and from late August to early September. The parasitic rate in the pesticide unsprayed fields were higher than those of sprayed fields during the pesticide spraying period, from July to August and parasitic activities were active from October to before coming winter.

• Toxicological Research
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• v.18 no.4
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• pp.331-339
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• 2002

Phenoxy compounds, 2,4-Dichlorophenol acetoxy acid (2,4-D) and 2,4-dichlorophenol (DCP), are widely used as a hormonal herbicide and intermediate for pesticide manufacturing, respectively. In order to assess the potential of these compounds as endocrine disruptors, we studied the androgenicity of them wing in vivo and in vitro androgenicity assay system. Administration of 2,4-D (50 mg/kg/day, p.o.) or DCP (100 mg/kg/day, p.o.) to rats caused an increase in the tissue weight of ventral prostate, Cowpers gland and glands penis. These increase of androgen-dependent tissues were additively potentiated when rats were simultaneously treated with low dose of testosterone (1 g/kg, s.c.). 2,4-D increased about 350% of the luciferase activity in the PC cells transiently cotransfected phAR and pMMTV-Luc at concentration of $10^{-9}$ M. In 2,4-D or DCP-treated castrated rats, testosterone 6$\beta$-hydroxylase activity was not significantly modulated even when rats were co-treated with testosterone. In vitro incubation of 2,4-D and DCP with microsomes at 50 $\mu$M inhibited testosterone 6$\beta$-hydroxylase activity about 27% and 66% in rat liver microsomes, about 44% and 54% in human liver microsomes and about 50% and 45% in recombinant CYP3A4 system, respectively. The amounts of total testosterone metabolites were reduced about 33% and 75% in rat liver microsomes, 69% and 73% in human liver microsomes and 54% and 64% in recombinant CYP3A4 by 2,4-D or DCP, respectively. Therefore, the additive androgenic effect of 2,4-D or DCP by the co-administration of the low dose of testosterone may be due to the increased plasma level of testosterone by inhibiting the cytochrome P450-mediated metabolism of testosterone. These results collectively suggested that 2,4-D and DCP may act as androgenic endocrine disrupter by binding to the androgen receptor as well as by inhibiting the metabolism of testosterone.

• Korean Journal of Agricultural Science
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• v.32 no.2
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• pp.215-221
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• 2005

The residual study of pesticide has been used in various areas, such as food safety, environmental protection, establishment of tolerance, and explaining the pathway and reaction mode of pesticides, and its importance was expected to increase further more. The aspect of food safety, the pesticide residue survey have been practiced at many organizations, but there were no verification of analytical results at present. In this experiment, we focused on instrumental stability, including response of each instrument and the recovery ratio of each organization's method. As samples for this experiment, we prepared cucumber and sesame, and chose 4 pesticides (bifenthrin, chlorpyrifos, diazinon, and ethoprophos), which were mostly detected from pesticide residue survey and widely used for each crop. The standard deviation of peak areas in the chromatogram of each pesticide were under 1.212 %, so it showed that most instruments were stable. The relationship of recovery ratio of each organization were over 0.996 for every pesticide and each organization. Finally, the analytical results for pesticide residue from each participated organization were not statically significant and we could put confidence in the result from each organization.

• Journal of Food Hygiene and Safety
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• v.33 no.2
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• pp.110-117
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• 2018

The aim of this study was to develop an analytical method for the quantification of diazepam residues in fishery products, using liquid and gas chromatography-tandem mass spectrometry (LC-MS/MS and GC-MS/MS). The sample utilized in the study was extracted from the fish sample (crucian carp) using 0.1% formic acid in acetonitrile. For the utilization of the purification process, the dispersive solid phase extraction (dSPE) was used for LC-MS/MS, dSPE and SPE was used for GC-MS/MS, respectively. To be sure, the standard calibration curves showed a good linearity as the noted correlation coefficients, $r^2$ was > 0.99. The average recoveries for accuracy ranged in 99.8~124% for the samples which were fortified at three different levels (0.001, 0.002 and 0.010 mg/kg). The correlation coefficient for the precision effect was measured at a range of 4.01~11.8%. The limit of detection (LOD) for the diazepam analysis was 0.0004 mg/kg, and the limit of the quantification (LOQ) was 0.001 mg/kg. The proposed analytical method was characterized with a high accuracy and acceptable sensitivity to meet the established Codex Alimentarius Commission (CAC/GL71-2009) guideline requirements. We therefore established the optimal analysis method for the determination of diazepam in the fishery products using LC-MS/MS and GC-MS/MS. It would be applicable to analyze the diazepam residues in fishery products in further studies on this subject.

• The Korean Journal of Pesticide Science
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• v.13 no.2
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• pp.117-125
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• 2009

Phenylformamidine derivatives are well known as insecticides for their specific activity against the insects. It has now been established that they show insecticidal activity as agonists on the octopamine receptor which is located in the synapse membrane. The reaction of triethylorthoformate and fluoroanilines gave formimidates (1) in good yields and N',N'-Disubstituted N-fluorophenylformamidine derivatives were synthesized more easily by using microwave. This microwave reaction condition gave products in high yields and faster reaction time than conventional methods. All the compounds were screened for their biological activity agaist harmful insects of plant hoppers, moths, aphids and mites. Synthetic compounds of 2-I-a, 2-I-c, 2-I-d, 2-II-d showed good activity against mites and plant hoppers.

• Korean Journal of Veterinary Research
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• v.17 no.2
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• pp.63-71
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• 1977

During the period of March, 1976 to December, 1976, 48 raw milk samples were taken from dairy cows at 48 different dairy farms in Korea analyzed by gas liquid chromatography to determine the seasonal variation of the amount of organochlorine pesticide residues. At the same time 80 market milk, 10 beef and 10 pork samples were analyed by the same procedure for checking residual levels. The results were summarized as follows; 1. Milk samples from 17 dairy farms (36 per cent of tatal) were shown to be contaminated with various organochlorine pesticides. The residua lrate of ${\gamma}-BHC$ in tested samples were 44per cent (14 sam ples) that of aldrine was 28 per cent (9 samples) and those of pp'-DDT, dieldrin and heptachlor were 9.3 percent (3 samples) respectively. 2. In raw milk pp'-DDT, ${\gamma}-BHC$, aldrin, dieldrin and heptachlor were detected, and aldrin, dieldrin and heptachlor were detected in the market milk. Any kinds of organochlorine pesticides were not detected in beef samples but dieldrin and heptachlor were detected in pork samples. Average residual values of aldrin, dieldrin and heptachlor in the market milk were 0.0077 ppm (0.0000~1.1100 ppm), 0.0001ppm (0.0000~0.0500 ppm) and 0.0008 ppm (0.0000~2.0520 ppm), respectively, and those of dieldrin and heptachlor in pork samples were 0.0010 ppm (0.0000~0.0100 ppm) and 0.0033 ppm (0.0000~0.0330 ppm). respectively. 3. Residues of organochlorine pesticides in raw milk were extremely variable; in fact pp'-DDT was detected in milk samples from A, B, C and D districts and endrin was not detected from all districts. The ${\gamma}-BHC$ and dieldrin were detected at the district of A, C and D, aldrin at the districts of A and C and heptachlor at the districts of both A and D. 4. Seasonal trends of residual values of organochlorine pesticides were, in general, noticeable. The residual level was much higher in Spring than in other seasons and showed the tendeney of decrease from spring through summer and autumn generally; in the case of pp'-DDT average residual values were 0.0121 ppm in spring, 0.0022 ppm in summer and not detected in autumn. But in winter ${\gamma}-BHC$ and aldrin residues were increased a little. Residual values in raw milk (when cow are fed on hay and silage) were appeared higher in winter than the other seasons. 5. Residues of organochlorine pesticides in raw milk were not related in respect to hygienic conditions of dairy farms pp'-DDT and heptachlor were, in general, detected in all farms and aldrin was more detected in milk from well sanitated farms than poor sanitated ones.

• Korean Journal of Environmental Agriculture
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• v.42 no.1
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• pp.71-81
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• 2023

An accurate and easy-to-use analytical method for determining isocycloseram and its metabolites (SYN549431 and SYN548569) residue is necessary in various food matrixes. Additionally, this method should satisfy domestic and international guidelines (Ministry of Food and Drug Safety and Codex Alimentarius Commission CAC/GL 40). Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) was used to determine the isocycloseram and its metabolites residue in foods. To determine the residue and its metabolites, a sample was extracted with 20 mL of 0.1% formic acid in acetonitrile, 4 g magnesium sulfate anhydrous and 1 g sodium chloride and centrifuged (4,700 G, 10 min, 4℃). To remove the interferences and moisture, d-SPE cartridge was performed before LC-MS/MS analysis with C₁₈ column. To verify the method, a total of five agricultural commodities (hulled rice, potato, soybean, mandarin, and red pepper) were used as a representative group. The matrix-matched calibration curves were confirmed with coefficients of determination (R²) ≥ 0.99 at a calibration range of 0.001-0.05 mg/kg. The limits of detection and quantification were 0.003 and 0.01 mg/kg, respectively. Mean average recoveries were 71.5-109.8% and precision was less than 10% for all five samples. In addition, inter-laboratory validation testing revealed that average recovery was 75.4-107.0% and the coefficient of variation (CV) was below 19.4%. The method is suitable for MFDS, CODEX, and EU guideline for residue analysis. Thus, this method can be useful for determining the residue in various food matrixes in routine analysis.

• Journal of Food Hygiene and Safety
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• v.34 no.2
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• pp.140-147
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• 2019

An analytical method was developed for the determination of quinoxyfen in agricultural products using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted with 1% acetic acid in acetonitrile and water was removed by liquid-liquid partitioning with $MgSO_4$ (anhydrous magnesium sulfate) and sodium acetate. Dispersive solid-phase extraction (d-SPE) cleanup was carried out using $MgSO_4$, PSA (primary secondary amine), $C_{18}$ (octadecyl) and GCB (graphitized carbon black). The analytes were quantified and confirmed by using LC-MS/MS in positive mode with MRM (multiple reaction monitoring). The matrix-matched calibration curves were constructed using six levels ($0.001-0.25{\mu}g/mL$) and the coefficient of determination ($R^2$) was above 0.99. Recovery results at three concentrations (LOQ, 10 LOQ, and 50 LOQ, n=5) were in the range of 73.5-86.7% with RSDs (relative standard deviations) of less than 8.9%. For inter-laboratory validation, the average recovery was 77.2-95.4% and the CV (coefficient of variation) was below 14.5%. All results were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and Food Safety Evaluation Department guidelines (2016). The proposed analytical method was accurate, effective and sensitive for quinoxyfen determination in agricultural commodities. This study could be useful for the safe management of quinoxyfen residues in agricultural products.