• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.3
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• pp.110-116
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• 2006

In this study, the biodegradation rate of paraoxon, that is an organophosphate pesticide, was enhanced by recombinant Escherichia coli harboring organophosphorus hydrolase (OPH). The optimum conditions were 8.5 of initial pH and 5.0% of acetone for the enhancement of specific whole cell OPH activity. When the OPH was produced to 498 Unit/L, 98% of 275mg/L paraoxon was degraded within 10 minutes, and thus the biodegradation rate was enhanced to $29.2mg/g{\cdot}min$. The results implied that practical bioremediation technology developed in this study was an effective method to degrade residual organophosphate pesticide in ground water or soils in a short time.

• The Korean Journal of Pesticide Science
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• v.4 no.4
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• pp.48-55
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• 2000

This study examined how does farm producers and urban consumers recognize the toxicity of pesticides application to agricultural production. The survey was carried out with quesuonnaires, and found tile fellowing results. The 60% of the total respondents in urban residents acknowledged that it is necessary for farming to apply pesticides. Nevertheless, they think that pesticides application have excessively been done more than necessary, and they would cause the problem of agrochemical-residual in agricultural products. They preferred to the crops produced by organic-farming. But they do not believe that the organic crops are pure one that pesticides are not applied at all. They thought that pesticides remained in the crops and they cause a chronic toxicity and cancer, though their degree of causing cancer would not be high. The other hand, farmers among the total respondents expressed that pesticides are absolutely needed to farming. However, about half of the total farmers' respondents did not follow the recommended guide line for proper use of pesticides and applied its double amount of the recommended dose. The most of farmers thought that the applied pesticides would be persisted into the crops. The 69 % of the total respondents did not know that crops over MRL(Maximum Residue Limit) of pesticides must be discarded and tile farmer who distributed the crops over MRL of pesticides have to pay some kind of penalty.

• Korean Journal of Agricultural Science
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• v.32 no.2
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• pp.223-231
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• 2005

In order to know the residual pattern of pesticides and predict to the degradation period until below MRL, we experimented diazinon, iprodinon and chlorfenapyr for shallot. They were the most detected pesticide in shallot by NAQS (National Agricultural product Quality management Service) survey. In this experiment, we sprayed those pesticides 15days before harvest and analyzed 0, 1, 2, 3, 5, 7, 10, 14 day sample to establish logical equation and to calculate $DT_{50}$. During the cultivating period, the residue amount of diazinon was changed from 1.02 mg/kg (0 day) to 0.01 mg/kg (14 day), $DT_{50}$ was 2.19 days, and iprodione was changed from 1.45 mg/kg (0 day) to 0.14 mg/kg (14 day), $DT_{50}$ was 4.15 days, and chlorfenapyr was changed from 1.5 mg/kg (0 day) to 0.01 mg/kg (14 day), $DT_{50}$ was 1.97 days. The $DT_{50}$ of double amount in those pesticides, diazinon was 2.24 days, iprodione was 4.82 days, and chlorfenapyr was 2.24 days, respectively.

• Journal of Korean Society on Water Environment
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• v.23 no.2
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• pp.193-200
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• 2007

The AOPs research defined by creating a sufficient amount of OH radicals from the dissolution of organic materials through photoxidation and research for a complete elimination of residual organic materials by membrane are actively ongoing. This research focuses on the hybrid processing of AOPs and M/F membrane to dissolve and eliminate organic chemicals in drinking water which are suspected of carcinogens. For this purpose, underground water was used as a source of drinking water for the hybrid processing of AOPs oxidation and M/F membrane, and a pilot plant test device was installed indoor. Carcinogenic chemicals of VOCs and pesticide were artificially mixed with the drinking water, which was then diluted close to natural water in order to examine treatment efficiency and draw optimal operation conditions. The samples used for this experiment include four chemicals phenol, chloroform, in VOCs and parathion, carbaryl in pesticide. As a result of the experiments conducted with simple, and compound solutions, the conditions to sufficiently dissolve and eliminate carcinogenic chemicals from the hybrid processing of where carcinogens were artificially added are : (hydrogen peroxide) prescribed solution 100 mg/L under pH 5.5~6.0, and the temperature $12{\sim}16^{\circ}C$, at the normal temperature and pressure. $d-O_3$ volume of 5.0 ppm and above and 30-40 minutes of reaction time are most appropriate and using MF/UF for membrane was ideal.

• The Korean Journal of Pesticide Science
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• v.16 no.1
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• pp.28-34
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• 2012

We analysed 149 samples of Korean traditional herbal tea materials. The 156 pesticides were analyzed by GC/ECD and NPD, detected pesticides were confirmed by GC-TOF/MS. Sample preparation was performed bv multi-residue analysis method of multiclass pesticides of the Korea Food Code. The residual pesticides were detected in 22 samples(14.8%), the highest detection frequency samples are lycium and jujube. Detected pesticides in Korean traditional herbal tea materials were chlorpyrifos (5 samples), chlorothalonil (3 samples), cypermethrin (3 samples), hexaconazol (3 samples) and cyhalothrin(3 samples). The pesticide types detected in Korean traditional herbal tea materials were organophosphorus(29.2%), pyrethroids(16.7%), organochlorines (12.5%) and triazoles(12.5%). The 5 samples(lycium, jujube, chrysanthemum, balloon-flower, milk vetch root) were detected pesticides below MRLs, 2 samples(cornus fruit, cnidium) were detected pesticides unnotificated MRLs.

• The Korean Journal of Pesticide Science
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• v.18 no.1
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• pp.1-7
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• 2014

The present study was performed to investigate the pre-harvest residue limit (PHRL) of pesticides namely, metalaxyl-M and flusilazole in oriental melon, and to identify the biological half-life and characteristics of their residues. In this study, pesticides were sprayed once as single spray and double spray on oriental melon. The oriental melon samples were collected at 0, 1, 2, 3, 5, 7, 9 and 11 days before harvest and samples were extracted with QuEChERS method. The residues of both the pesticides were quantified using GC/NPD and LC/MS/MS. The limit of detection was found to be 0.02 mg/kg and 0.01 mg/kg and their recoveries were greater than 95% (95.7% ~ 103.2% for metalaxyl-M and 100.2% ~ 106.8% for flusilazole) for both pesticides. The biological half-lives of both metalaxyl-M and flusilazole were 12 days at single and double spray, respectively. The PHRL of metalaxyl-M and flusilazole was found 1.0 mg/kg and 0.3 mg/kg, respectively for 10 days before harvest. The results of the present study shows the residual level of both the pesticides metalaxyl-M and flusilazole in oriental melon were less than their maximum residual limits.

• The Korean Journal of Pesticide Science
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• v.12 no.1
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• pp.34-42
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• 2008

In order to know the residual pattern of some pesticides and predict to the degradation period until below MRL, we experimented chlorothalonil, indoxacarb, lufenuron, metalaxyl and methomyl for Chinese cabbage. They were frequently detected pesticides in Chinese cabbage by NAQS (National Agricultural product Quality management Service) monitoring survey. In this experiment, we sprayed those pesticides 10days before harvest and analyzed 0, 1, 2, 3, 5, 7, 10 day samples to establish logical equation and to calculate $DT_{50}0$. During the cultivating period, the residue amount of chlorothalonil was changed from $55.58\;mg\;kg^{-1}$ (0 day) to $20.08\;mg\;kg^{-1}$ (10 day), $DT_{50}$ was 7.45 days, indoxacarb was $7.85\;mg\;kg^{-1}$ (0 day) to $1.46\;mg\;kg^{-1}$ (10 day), and 4.2 days, lufenuron was $1.57\;mg\;kg^{-1}$ (0 day) to $0.49\;mg\;kg^{-1}$ (10 day), and 5.85 days, metalaxyl was $8.12\;mg\;kg^{-1}$ (0 day) to $0.10\;mg\;kg^{-1}$ (10 day), and 175 days, and methomyl was $11.51\;mg\;kg^{-1}$ (0 day) to $0.80\;mg\;kg^{-1}$ (10 day), and 2.42 days at single dose application, respectively. The $DT_{50}$ of double amount in those pesticides were 9.05 days in chlorothatonil, 7.09 days in indoxacarb, 8.82 days in lufenuron, 3.32 days in metalaxyl, and 2.72 days in methomyl, respectively.

• The Korean Journal of Pesticide Science
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• v.17 no.2
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• pp.84-93
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• 2013

Validated analytical methods for isopyrazam are meager or lacking. In the present study, a single residual analytical method was developed for isopyrazam in selected commodities. Isopyrazam was analyzed in brown rice, soybean, green pepper, mandarin, cucumber, and Korean melon. We tried different solvents and methods through extraction, partition and purification steps to obtain best analytical results. For isopyrazam samples were extracted with acetonitrile, concentrated and partitioned with n-hexane, clean-up using florisil with n-hexane/ethylacetate (70/30) and analyzed with HPLC/UVD. The limit of quantitation (LOQ) for isopyrazam was 1.0 ng (S/N > 10) and method LOQ (MLOQ) was 0.04 mg $kg^{-1}$. Recovery ranged through 81.0~105.3% (syn-isomer) and 80.8~105.6% (anti-isomer) at fortification level of 0.04 (MLOQ), 0.4 (10 ${\times}$ MLOQ), and 2.0 (50 ${\times}$ MLOQ). The coefficient of variation (CV) for isopyrazam was less than 10% regardless of sample types. These results were further confirmed with LC/MS, respectively. The proposed method is highly reproducible and sensitive and is suitable for routine analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.375-381
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• 2018

This study was performed to investigate the residual characteristics of the insecticide dinotefuran in asparagus under greenhouse conditions from July to August and consequentially to obtain basic data for guidelines on the safe use of this pesticide in asparagus. Residues of dinotefuran in young stem of asparagus before and after growing mother stem were analyzed from samples collected at 0, 1, 3, 5, and 7 days after single application of a commercial formulation of dinotefuran (wettable powder, 10%) at the recommended dose (2,000 times dilution). The residue of dinotefuran in young stem of asparagus was analyzed by HPLC-UVD, and recovery of dinotefuran in young stem was tested at 0.5 and 1.0 mg/kg concentrations. As a result, the limit of quantitation (LOQ) of dinotefuran was 0.01 mg/kg, and the recovery of dinotefuran was in the range of 83.3-94.0% with a coefficient of variation less than 10%. Residues of dinotefuran in young stem of asparagus before and after growing the mother stem were lower than the tentative limit (0.05 mg/kg) from 5 and 3 days after single application, respectively. Based on these results, single application of dinotefuran (wettable powder, 10%) at the recommended dose at 7 days before harvest would have no deleterious effects on safety issues concerning pesticide residue. This result might provide basic information to construct guidelines for the safe use of dinotefuran in asparagus.

• The Korean Journal of Pesticide Science
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• v.16 no.2
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• pp.131-136
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• 2012

This study was carried out to elucidate residual characteristics of azoxystrobin and difenoconazole in fresh ginseng. Test pesticides were sprayed onto ginseng both in 2009 for 3-year-old ginseng and in 2010 for 4-year-old ginseng according to their pre-harvest intervals (PHIs). Limit of quantitation (LOQ) of both azoxystrobin and difenoconazole was 0.003 mg/kg. Analytical methods set up for the test pesticides were considered to be suitable for the analysis of their residues in fresh ginseng, considering that their recoveries ranged from 87.58 to 112.79%. Concentration of azoxystrobin in 3-year-old ginseng ranged from 0.004 to 0.011 mg/kg and that in 4-year-old ginseng ranged from 0.007 to 0.016 mg/kg. Amounts of difenoconazole in 3- and 4-year-old ginsengs were from 0.003 to 0.007 and from 0.007 to 0.01 mg/kg, respectively, representing no accumulation effect observed in residue amount between them.