• Korean journal of applied entomology
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• v.26 no.3 s.72
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• pp.151-157
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• 1987

The toxicities of binary mixtures of the four insecticides acephate, demeton-S-methyl, cypermethrin and pirimicarb to the two strains of green peach aphid (Myzus persicae Sulz.) resistant to acephate and demeton-S-methyl were investigated and compared to the toxicities of their individual insecticides. The synergistic action of the insecticide mixtures to the insects were greatly varied with the kind of insecticide combinations, their mixture ratios, and the origin of resistance by an insecticide. The maximum synergistic action of acephate for the acephate resistant strain was obtained at 1:1 mixed with demeton-S-methyl. However, there were some antagonistic effects in all acephate mixtures with pirimicarb and cypermethrin. With the strain of demeton-S-methyl resistance, acephate, cypermethrin, and pirimicarb were synergized at the given mixture ratios by demeton-S-methyl. The maximum synergistic effect was observed at 2:3 with acephate, 1:1 with cypermethrin and 3:2 with pirimicarb.

• Korean journal of applied entomology
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• v.28 no.1
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• pp.32-36
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• 1989

The joint toxic action of mixtures of cypermethrin or pirimicarb with one of other insecticides (acephate, cypermethrin, demeton-S-methyl and pirimicarb) on the cypermethrin or picimicarb-selected green peach aphid (Myzus persicae Sulzer)was investigated. The responses depended on the choice and ratios of insecticide combination. In the cypermethrin-selected strain bioas-say, mixtures of test insecticides showed no synergistic effect. On the other hand, the maxi-mum synergistic effects for the pirimicarb-selected strain were obtained at the 8 : 2 ratio of pirimicarb and demeton-S-methyl exhibited antagonistic effect.

• Journal of Food Hygiene and Safety
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• v.9 no.4
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• pp.185-189
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• 1994

This study was to investigate time-dependent degradation process under various pH condition for organophosphorus(org-p) insecticides, namely Demeton-s-methyl, diazinon, Parathion, Phenthoate, and EPN in several waters. They were analysed by GC-FTD according to standard methods for the examination of water and wastewater. In pH=4, diazinon showed disappearance after 14 days in chromatogram. In pH=11, org-p insecticides were almost degradable after 7 days. In this condition, effect of pH on degradation process was greater than of light. In pH=7, org-p insecticides persisted residues after 112 days except Demeton-s-methyl. In BOD5 120, 250 ppm and domestic water, org-p insecticides showed also rapid degradation process.

• Analytical Science and Technology
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• v.18 no.3
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• pp.224-231
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• 2005

In this study, the optimum conditions for the LPME (liquid phase microextraction) were investigated to overcome several shortcomings of traditional liquid-liquid extraction method. The LPME, which is automatic and dynamic, was used to analyze the five pesticides (dementon-S-methyl, diazinon, parathion, fenitrothion, EPN) extracted from vegetable, and HP 6890 GC/NPD was used as an analytic instrument. It was possible to optimize the extraction condition using the automatic LPME. The optimum extraction rate was obtained at pH 3.0 and $100{\mu}g/mL$ of salt concentration and standard curve showed linearity with over $R^2=0.9921$ in the range of $0.2{\sim}10{\mu}g/g$. The relative standard deviations were 7.7%, 9.8%, 7.8%, 9.7% and 8.2% in the $5.0{\mu}g/g$ concentration of dementon-S-methyl, diazinon, parathion, fenitrothion and EPN, respectively. The acquired accuracies were satisfactory showing 12.7%, 7.8%, 10.4%, -6.7% and -0.7% for dementon-S-methyl, diazinon, parathion, fenitrothion and EPN respectively.

• Korean Journal of Environmental Agriculture
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• v.31 no.3
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• pp.277-285
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• 2012

BACKGROUND: For safety evaluation of imported agri-food in Korea, the multiresidue analysis method was establised for unregistered organophosphorus pesticides, aspon, chlorthion, chlorthiophos, crotoxyphos, demeton-O, demeton-S, demeton-S-methyl, dioxathion, heptenophos, iodofenphos, leptophos, methyl-trithion, propetamphos and sulfotep. METHODS AND RESULTS: The used method for multiresidue analysis in brown rice and orange used as representative samples of imported agri-food was the official method of Korean Food and Drug Administration. The results of validation test of 13 organophosphorus pesticides except crotoxyphos for multiresidue analysis method are compared to the criteria such as specificity, linearity, accuracy, precision and limit of quantification. CONCLUSION: The used method for multiresidue analysis of unregistered 13 organophosphorus pesticides except crotoxyphos in Korea can surely be used as an official method for routine analysis of imported agri-food.

• Korean Journal of Environmental Agriculture
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• v.8 no.1
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• pp.47-54
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• 1989

This study was conducted to investigate insecticide toxicities to a honeybee, Apis cerana F. being raised in Korea and its detoxifying enzyme activities. In order to determine the appropriate usage of insecticides, median effective dose and detoxifying enzyme activities to seven insecticides were observed. Various detoxifying enzymes, including microsomal oxidases, glutathione S-transferases, esterases, and DDT-dehydrochlorinase were assayed in the midguts of adult worker bees as the enzyme source. Of the insecticides used, $LC_{50}$ value in DDT treatment was the highest as 19ppm, and that in EPN treatment was the lowest as 0.75ppm. Sublethal exposures of honeybees to various insecticides had some effects on microsomal enzyme activities. Aldrin epoxidase activity was inhibited by malathion and demeton S-methyl treatment. N-demethylase activity was induced by carbaryl treatment. Of the glutathione S-transferases, aryltransferase(DCNB conjugation) activity was significantly induced by diazinon, and moderately induced by malathion. Of the esterases, ${\alpha}-NA$ esterase activity was moderately inhibited by malathion and permethrin. Carboxylesterase and acetylcholinesterase activity were not affected by the sublethal exposure of honeybee to the insecticides. Sublethal exposure of honeybee to the insecticides had no effect on DDT- dehydrochlorinase activity, except carbaryl, malathion and demeton S-methyl were inhibited.

• Korean journal of applied entomology
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• v.28 no.1
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• pp.23-27
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• 1989

The green peach aphid(Myzus pericae Sulzer) was selected over 20 generations with cypermethrin and pirmicarb, respectively. The resulting resistant strains were tested to inverting-ate the development of insecticide resistance and cross-resistance to some insecticides in the laboratory. The development of insecticide resistance against green peach aphid at the 20th selected generation was greatly varied with the insecticides: 20.5 fold for cypermethrin and 3.2 fold for pirimicarb compared with the parent strain. The cypermethrin selected strain exhibited cross resistance to acephate and pirimicarb, and pirimicarb selected strain to acephate and cypermethrin, respectively. Demeton-S-methyl, however, has not been shown cross-resistance by the selected strains.

• Korean journal of applied entomology
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• v.34 no.2
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• pp.89-94
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• 1995

Resistance mechanism of organophosphorus insecticides (OPs) in the spiraea aphid, whose populations were originated from several apple orchards where various OPs were frequently sprayed, was investigated. For Wonju population to which insecticides were not sprayed, resistance ratios (BRs) for pirimicarb, phosphamidon, and demeton S-methyl re 49, 31, and 5, respectively. However, for Yesan population to which OPs were sprayed 5 times, RRs for pirimicarb, phosphamidn, and dementon were 830, 536, and 204, respectively. The esterase activities of Wonju and Yesean populations increased by 44.5 and 92.0% compare to that of Kwagju population. R/S a values (S clone Kwangju population; R clone: Iechon opulation) for acetylcholinesterase (AChE) inhibition (${I}_{50}$) by pirimicarb and phosphamidon were 299.2 and 186.0, respectively. Our results indicate that increase of esterase activity and reduction of AChE sensitivity seemed to contribute insecticide resistance of the spiraea aphid.

• Korean Journal of Environmental Agriculture
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• v.3 no.2
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• pp.30-36
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• 1984

This study was to investigate the organophosphorus insecticide residues in crops including five kinds of vegetables and two kinds of fruits. The pesticides investigated in spring-radish, spring Chinese cabbage, cucumber and tomato were diazinon, DEP and malathion, in unripe pepper EPN and PAP, in peach EPN, parathion and demeton-methyl, and in grape EPN, PAP and MEP. All samples were analysed by gas chromatographic technique with NPD detector. No one sample was found to approach proposed national maximum residue limits in Korea.

• YAKHAK HOEJI
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• v.54 no.6
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• pp.429-440
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• 2010

HS-SPME-GC/MS was studied and optimized for the determination of 17 orgarnophosphorous pesiticides (OPPs: chlorpyrifos, chlorpyrifos-methyl, demeton-s-methyl, diazinon, dimethoate, EPN, fenitrothion, fenthion, malathion, methidathion, monocrotophos, parathion, phenthoate, phosphamidon, sulfotep, terbufos, triazophos) in blood. Optimum SPME parameters were selected: choice of SPME fiber (85 ${\mu}m$ polyacrylate), pH effect (0.5 N HCl), salt effect ($Na_2SO_4$, 0.2 g; 20%), headspace incubation temperature ($80^{\circ}C$), headspace incubation time (1 min), headspace adsorption time (30 min) and GC desorption time (2 min). These parameters were optimized using HS-SPME autosampler coupled with gas chromatography-mass spectrometry (GC-MS). Method validation was carried out in terms of linearity, limit of detection (LOD), limit of quantitation (LOQ) and recovery in blood. The assay was linear over 0.5~5.0 mg/l ($r^2$=0.955~1.000). Limit of detection (LOD) and limit of quantitation (LOQ) in blood were determined 0.03~0.3 mg/l (S/N=3) and 0.1~1.1 mg/l (S/N=10), respectively. Relative recovery with 0.5, 1 and 5 mg/l (in blood) were 90.8%, 98.5% and 94.1%, respectively. This method will be applied to the determination of the orgarnophosphorous pesticides in postmortem blood. The proposed protocol can be an attractive alternative to be used in routine toxicological analysis.