• Journal of the Korean Chemical Society
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• v.30 no.5
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• pp.465-474
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• 1986

The solvent extraction and cleanup processes for the simultaneous gas-liquid chromatographic determination of 11 kinds of organophosphorous pesticide residues in crops were investigated. The extracts dissolved with acetone were partitioned with petroleum ether after adding saturated NaCl solution. Evaporated the partitioning solvent, the residue was dissolved in methylene chloride and eluted through mixed adsorbent (1 : 2 : 4 of activated carbon, magnesia and diatomaceous earth) with methylene chloride as an eluent. The pesticides recovered were 82∼105% and the impurities were effectively removed.

• Toxicological Research
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• v.20 no.4
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• pp.329-337
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• 2004

Primiphos-methyl and methidathion as organophosphorus (OP) pesticides were tested for their immunotoxic effects on Balb/c mice. Three dose levels of primiphos-methyl (10, 60, or 120 mg/kg/day) and methidathion (0.5, 2.5 or 5.0 mg/kg/day) were administered orally in the mice for 4 weeks. After, changes in body weight gain, relative weight of spleen and thymus, viable splenic cell numbers, surface marker on immune cell, and proliferation activity were investigated. Results showed that neither Pirimiphos-methyl nor methidathion dosages changed significantly body weight, relative thymus and spleen weight, and thymus and spleen cellularities of the mice, but high dose treatment (120 mg/kg) of pirimiphos-methyl significantly decreased relative spleen weight and spleen cellularity of the mice. No alterations were observed in changes of LPS-proliferation response of splenocytes by exposure to any dose of pirimiphos-methyl and methidathion. However, pirimiphos-methyl dosages reduced ConA-proliferation response of splenocytes and both methidathion and pirimiphos-methyl decreased the ability of antibody production to SRBC. The results indicate that 28 days exposure to the high dose of pirimiphos-methyl suppress the function of splenic T and B cell function, and methidathion reduce the immune responsibility of B cell in mice without the changes in lymphoid organ weight or viability of splenocytes. Pirimiphos-methyl is more immunotoxic than methidathion although this has higher general toxicity than that.

• Journal of Environmental Health Sciences
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• v.24 no.3
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• pp.99-106
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• 1998

This study was performed to investigate the bioconcentration of dichlorvos, methidathion and phosalone in zebrafish (brachydanio rerio), red sword tail(Xiphophorus hellieri). The fishes were exposed to 0.05 ppm, 0.01 ppm, 0.50 ppm, one-hundredth concentration of 96-hrs LC$_{50}$ and one-thousandth concentration of 96-hrs LC$_{50}$ and test periods were 3, 5 and 8 days. The deputation rate of each pesticide from the whole body of fish was determined over the 24-hr period after treatment. Obtained results are summerized as follows: In the case of dichlorvos, dichlorvos concentration in zebrafish extract and BCF$_{s}$ of dichlorvos were increased as increasing test concentration. In the case of same experimental concentrations, dichlorvos concentration in zebrafish extract and BCF$_{s}$ of dichlorvos were decreased as proloning test periods, especially dropped after 5days. Dichlorvos concentration in red sword tail extract were increased as increasing test concentration, lyat BCF$_{s}$ in concentration of 0.05 ppm, 0.01 ppm and one-hundredth of 96-hrs LC$_{50}$ were decreased. Methidathion and phosalone concentration in zebrafish extract in zebrafish extract were increased as increasing test concentration, but there was little difference in BCF$_{s}$. In the case of same experimental concentrations, there were little differences in BCF$_{s}$ and concentration in zebrafish extract. In the case of red sword tail, it was impossible to calculate on BCF$_{s}$ data because test concentration was under the detecting limit on GC or test fish were die. Determined deputation rate conatant were highest on dichlorvos, and followed by methidathion, and phosalone. The results of determining depuration rate of these pesticides showed that the high BCF in fish might be due to the slow depuration rate in fish, it is thought to be responsible for vapor pressure, water solubility and partition coefficient. It is suggested that one-hundredth concentration of 96-hrs LC$_{50}$ will be proper test concentration because one-thousundth of LC$_{50}$ was under the detecting limit on GC. Dichlorvos, methidathion and phosalone, organophosphorous pesticides, were examined to their BCF$_{s}$ and depuration rates by means of fish test.

• Journal of Preventive Medicine and Public Health
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• v.26 no.2 s.42
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• pp.268-281
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• 1993

The aquatic quality of the Naktong river after two or three months in June, 1991 with phenol spillage from a electrical factory in Kumi was investigated. The samples were collected at six sites of the Naktong river basin and Kachang and Kongsan lakes. Phenol was not detected from all water samples. Turbidity was very much increased to the down stream in the Naktong river. The BOD and COD values exceeded the 2nd grade(3mg/l) of the Korean standard quality of Environmenal Water Act at the all sampling sites of the Naktong river. Especially, the value of COD at Kaejin (12.5mg/l) was poorly classified as to the 5th grade of water class for the environmental quality standards. Organophosphorous pesticides such as parathion, malathion, fenitrothion and diazinon were investigated but not detected. Diazinon was only detected at the Ilsan bridge(1.42ppb), Okkye stream(6.95ppb), Waekwan bridge(0.32ppb), Gangjung reservior(0.13ppb), Kaejin (0.05ppb). Of the carbamates such as carbanyl, isoprocarb and cabofuran, the carbofuran was detected all sites except tap water, and Kachang and Kongsan lakes. The content of heavy metals such as Cd, Pb, Zn, Fe, Mn, Hg were not exceeding for drinking water standards at the all sampling region, but only mecury was detected from Okkye stream(0.018ppb) and Kaejin (0.09ppb). In the regions of Kachang and Kongsan lakes, the content of heavy meatals were lower than that of reservior of Naktong river.

• The Korean Journal of Pesticide Science
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• v.11 no.4
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• pp.320-330
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• 2007

Mitochondrial 16S DNA sequences of Bemisia tabaci which were collected on rose greenhouse of Iwol and Jinchen in Chungbuk and red pepper field of Miryang, Gyeongnam, were analyzed. The mtCOI PCR product of B. tabaci collected on red pepper field of Miryang were digested with EcoT14I (Sty I) into two fragments 555bp and 311bp, while the PCR product of B. tabaci collected on rose greenhouse of Iwol were digested with Sty I into two fragments of 560bp and 306bp. As a result, B. tabaci collected on red pepper reveal biotype Q and those on rose greenhouse was biotype B. These was difference between two biotypes in insecticide susceptibility, and the biotype B was more susceptible than biotype Q. As a result of foliar systemic test, root-uptake systemic test and residual effect, the biotype B was more susceptible. In case of inhibition effect on enzyme activities of fenitrothion (organophosphorous) and fenothiocarb (carbamate), those of biotype Q was higher than those of biotype B. These results indicate that biotype Q was more resistant than biotype B against 12 insecticides.

• The Korean Journal of Pesticide Science
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• v.16 no.2
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• pp.163-170
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• 2012

Nineteen registered insecticides including 8 mixed formulations with buprofezin and 11 single formulations which is not including buprofezin were evaluated by spray application for their toxicity against adult and nymph of citrus mealybug, Planococcus citri. Five mixed formulations with buprofezin such as buprofezin 15EC+acetamiprid 4EC, buprofezin 10SC+clothianidin 3SC, buprofezin 20WP+dinotefuran 15WP, buprofezin 20SC+thiacloprid 5SC, and buprofezin 20SC+thiamethoxam 3.3SC showed high insecticidal activity (>93%) against nymph and adult of P. citri. Insecticidal activities of EPN 45EC, fenitrothion 50EC and methidathion 40EC in organophosphorous group showed 90 to 93% against nymph only. In addition to, insecticidal activities of acetamiprid 8WP, clothianidin 8SC, dinotefuran 20WG and thiamethoxam 10WG in neonicotinoids group showed above 90% against nymph only. In systemic and residual effect, five mixed formulations that was already proved to have high insecticidal activity showed low toxicity with below 60% against $3^{rd}$ instar nymph of P. citri in tomato and rose under greenhouse. Control efficacy of five mixed formulations with buprofezin was above 90%, 80% and 70% at 5 days after treatment (DAT), 10 DAT and 15 DAT, respectively.

• The Korean Journal of Pesticide Science
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• v.18 no.3
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• pp.148-155
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• 2014

The transfer pattern of chlorpyrifos present in soil to cucumber plants were assessed and reported with plant growth, concentration dependency, and duration. Cucumber seedlings cultivated in a growth chamber for 30 days and a greenhouse for 120 days. Weight and length of cucumbers cultivated in the chamber increased with the increasing time, while the uptake of chlorpyrifos by cucumber increased a period from 0 to 15 days and decreased after 15 days. Uptake rates of chlorpyrifos into a cucumber plant were 1.0~1.3% to initial amounts treated with 20 and 40 mg/kg to soil. Most chlorpyrifos residues were detected in root, followed by stem and leaf. Results of the greenhouse test showed that chlorpyrifos amounts in cucumber fruits were present less than LOQ (0.02 mg/kg), and chlorpyrifos was mainly found in the root of the cucumber plant. Chlorpyrifos absorbed in a cucumber under greenhouse condition was smaller than that in chamber condition as 0.03~0.04%. Degradation patterns of chlorpyrifos in soils were similar during indoor and outdoor tests with half-lives of 25.8~73.0 days. These results may be useful for establishing the management strategy of residual pesticides in soil environment.

• Journal of Food Hygiene and Safety
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• v.14 no.4
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• pp.339-345
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• 1999

The present study was performed to investigate photodegradation rate constants and degradation products of dichlorvos and methidathion by the USEPA method. The two pesticides were very stable in sunlight for 16 days from September 2 to 18, 1998 and humic acid had no sensitizing effect on the photolysis of each pesticide in sunlight. The photolysis rate was fast-est for methidathion, followed by dichlorvos in the presence of UV irradiation. Photodegradation rate constant and half-life of dichlorvos were 0.0208 and 33.3 min, respectively. Photodegradation rate constant and half-life of methidathion were 0.6789 and 1.0min, respectively. The two pesticides were degraded completely in the presence of UV irradiation and UV irradiation with TiO$_2$in about 3 hours. Therefore, it is suggested that UV treatment will be effective for the degradation of pesticides in the process of drinking water purification. In case of dichlorvos and methidathion, UV irradiation with TiO$_2$was more effective for degradation than W irradiation. In order to identify photolysis products, the extracts of degradation products were analyzed by GC/ MS. The mass spectrum of photolysis products of dichlorvos was at m/z 153, those of the photolysis of methidathion were at m/z 198 and 214, respectively. Photolysis products of dichlorvos was Ο, Ο-dimethyl phosphate(DMP), those of methidathion were Ο, Ο-dimethyl phosphorothioate(DMTP) and Ο, Ο-dimethyl phosphorodithioate (DMDTP).

• Korean journal of applied entomology
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• v.31 no.3
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• pp.205-240
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• 1992

In reality, it is a green revolution of the entire agricultural matrix in Korea that integrated pest control plays an important role in the possible breakthrough in rice self-sufficiency. In paddy agroecosystem as man-modified environment, rice is newly established every year by transplantation under diverse water regimes which affect a microclimate. Standing water benefits rice by regulating the microclimate, but it favors the multiplication of certain pets through the amelioration of the microclimate. Further, the introduction of high yielding varieties with the changing of cultural practices results in changing occurrence pattern of certain pests. In general, japonica type varieties lack genes resistant to most of the important pests and insect-borne virus diseases, whereas indica type possesses more genes conferring varietal resistance. Thus, this differences among indica type, form the background of different approaches to pest management. The changes in rice cultivation such as double cropping, growing high-yielding varieties requiring heavy fertilization, earlier transplanting, intensvie-spacing transplanting, and intensive pesticide use as a consequence of the adoption of improves rice production technology, have intensified the pest problems rather than reduced them. The cultivation of resistant varieties are highly effective to the pest, their long term stability is threathened because of the development of new biotypes which can detroy these varieties. So far, three biotypes of N. lugens are reported in Korea. Since each resistant variety is expected to maintain several years the sequential release of another new variety with a different gene at intervals is practised as a gene rotation program. Another approach, breeding multilines that have more than two genes for resistance in a variety are successfully demonstrated. The average annual rice losses during the last 15 years of 1977-’91 are 9.3% due to insect pests without chemical control undertaken, wehreas there is a average 2.4% despite farmers’insecticide application at the same period. In other words, the average annual losses are prvented by 6.9% when chemical control is properly employed. However, the continuous use of a same group of insecticides is followed by the development of pest resistance. Resistant development of C. suppressalis, L. striatellus and N. cincticeps is observed to organophosphorous insecticides by the mid-1960s, and to carbamates by the early 1970s in various parts of the country. Thus, it is apparent that a scheduled chemical control for rice production systems becomes uneconomical and that a reduction in energy input without impairing the rice yield, is necessarily improved through the implementation of integrated pest management systems. Nationwide pest forecasting system conducted by the government organization is a unique network of investigation for purpose of making pest control timely in terms of economic thresholds. A wise plant protection is expected to establish pest management systems in appropriate integration of resistant varieties, biological agents, cultural practices and other measures in harmony with minimizing use of chemical applications as a last weapon relying on economic thresholds.

• Journal of the Korean Chemical Society
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• v.39 no.12
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• pp.902-909
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• 1995

Detection limit as well as calibration curves on organophosphorus pesticide(dimethoate, diazinon, parathion-methyl, fenitrothion, malathion) and BHCs were measured for evaluation of utility on qualitative or quantitative analysis of pesticides with ion Trap mass spectrometer and quadrupole mass spectrometer. As ionization source, EI and CI were adopted for qualitative analysis of pesticides by comparison of each fragmentation pattern. At the same time, the utility as trace analysis techniques through scan or selected ion monitoring(SIM) mode was evaluated. With ion trap for all pesticides, detection limit(DL, 1 ${\mu}L$ injection) on scan mode was ranged 0.008∼0.225 ng at signal to noise ratio 3. With quadrupole DL on scan mode was ranged 0.23∼3.1 ng over 0.032∼0.68 ng on SIM mode. The calibration curve with ion trap generated good linearity over 0.99 as correlation coefficient. As clean up procedure, Bio Beads S-X3 was used for the separation of oils from five organophosphorous pesticides in flour extractant showing more than 80% as recovery at most cases. In case of BHCs in jinseng with Florisil column, the recovery of pesticides has been 60% to 90%.