• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.446-452
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• 2011

BACKGROUND: To investigate the dissipation patterns of 3 pesticides, azoxystrobin, difenoconazole and iprodione, on green garlic after field treatment pesticides were treated as foliar treatment by single application at recommended and double the recommended rates. METHODS AND RESULTS: Residue samples were harvested at 0, 1, 2, 5, 7 and 10 days post-treatment for azoxystrobin and 0, 1, 2, 5, 7, 10, 15 and 21 days post-treatment for difenoconazole and iprodione. After preparation the fortified samples were extracted and analyzed by gas chromotography-electron capture detector (GC-ECD) to determine the residue levels. Recoveries ranged from 87 to 109% for azoxystrobin, difenoconazole and iprodione at two different levels. The limit of Quantification (LOQ) values were 0.002 mg/kg for azoxystrobin and difenoconazole and 0.01 mg/kg for iprodione. CONCLUSION(S): Half-lives of azoxystrobin, difenoconazole and iprodione in green garlic after treatment were 1.2, 3.8 and 3.2 days at recommended and 1.4, 3.3 and 3.2 at double the recommended rate, respectively. Residue level of azoxystrobin, difenoconazole and iprodione in green garlic were below the maximum residue limits (MRLs) at 0 day, 0 day and 5 days, respectively. Therefore, these pesticide were considered that residues was satisfied to the requirement of domestic trade related to the consumer safety.

• The Korean Journal of Pesticide Science
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• v.14 no.2
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• pp.95-103
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• 2010

Fomesafen is a selective herbicide, and used to control annual and perennial broad-leaf grass on soybean and fruit fields in USA and China, but not introduced in Korea yet. So, MRL (Maximum Residue Level), and analytical method of fomesafen were not establishment in Korea. Therefore, this experiment was conducted to establish a determination method for fomesafen residue in crops using HPLC-UVD/MS. Fomesafen 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 fomesafen from the aqueous phase. Florisil column chromatography was additionally employed for final clean up of the extract. The fomesafen was quantitated by HPLC with UVD, using a Shiseido CAPCELL-PAK UG C18 column. The crops were fortified with fomesafen at 3 levels per crop. Mean recovery ratio were ranged from 87.5% for a 0.4 ppm in hulled rice to 102.5% for a 0.4 ppm in apple. The coefficients of variation were ranged from 0.6% for a 2.0 ppm in hulled rice to 7.7% for a 0.04 ppm in green pepper. Quantitative limit of fomesafen was 0.04 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 fomesafen in agricultural commodities.

• The Korean Journal of Pesticide Science
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• v.17 no.1
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• pp.13-19
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• 2013

Isopyrazam, a new pyrazolecarboxamide fungicide developed by Syngenta, was highly active against foliar powdery mildew pathogens on cucumber, oriental melon and various vegetables. Following foliar applications on cucumber and oriental melon, crop residues were determined using high performance liquid chromatography. For all studies, limit of quantification was 0.02 mg/kg and minimum detection level was 2.0 ng and recoveries were 83.0-88.0% on cucumber, 92.4-104.5% on oriental melon. Isopyrazam was detected 0.07-0.72 mg/kg on cucumber and < 0.02-0.68 mg/kg on oriental melon, respectively. The TMDI (Theoretical Maximum Dailly Intake) of isopyrazam on cucumber and oriental melon was estimated to less than 1.765% of ADI.

• The Korean Journal of Pesticide Science
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• v.19 no.3
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• pp.185-194
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• 2015

This study was performed to establish a single residue analytical method for determining fungicide carpropamid residues in various agricultural commodities. Korean cabbage, apple, brown rice and green pepper were selected as representative crops. Samples were homogenized, extracted with acetone and purified by liquid-liquid partition and Florisil column chromatography. Carpropamid residues were analyzed at 220 nm with reversed phase HPLC equipped octylsilyl and octadecylsilyl column and confirmed using mass spectrometry. ILOQ (Instrumental limit of quantitation) of carpropamid was 2 ng and MLOQ (Method LOQ) was 0.02 mg/kg. Mean recoveries from four kinds of crop samples fortified at three levels (MLOQ, 10LOQ, 100LOQ) in triplicate were in the range of 84~112%. Relative standard deviations of the analytical method were all less than 10%, irrespective of crop types.

• Analytical Science and Technology
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• v.7 no.3
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• pp.395-402
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• 1994

Benomyl(Methyl-1-(Butyl Carbamoyl)-Benzimidazole-2-yl-Carbamate) is widely used as pre- and post-harvest pesticide. It converts into MBC(Carbendarzime:Benzimidazole-2-yl-carbamate) and butyl-isocyanate in mild condition. In this study, three analytical methods for MBC were compared in view of detectability, correctness, and sensitivity. The first and second are HPLC analytical method employing the UV detection of MBC. Our new third method was modification of PFBB(pentafluoro-benzylbromide) derivatization method with GC-ECD & MSD. The average recoveries and detection limit of MBC in the newly modified method are 95% and $0.001{\mu}g/g$ in whole bean and bean sprouts respectively. This new method prevent pesticide analysis from misdetecting in bean and bean sprouts.

• Korean Journal of Environmental Agriculture
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• v.42 no.2
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• pp.131-138
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• 2023

The biological half-life and dissipation rate of azoxystrobin in crown daisy were calculated to establish the pre-harvest residue limits (PHRLs). The pesticide residues were calculated after washing with five different processes to propose an effective process in the household and conducted a risk assessment to confirm dietary safety. Azoxystrobin was sprayed according to the critical good agricultural practices (cGAP) in two different field trials, and the samples were harvested 7 times. The limit of quantitation was 0.02 mg/kg, and the mean recoveries of azoxystrobin were within the range of 70~120% with below 20% coefficient variation at the concentration of 0.02 and 0.2 mg/kg . The biological half-lives were 7.4 and 4.7 days, and the dissipation rate constants were 0.0872 and 0.1217 in fields 1 and 2, respectively. The average removal rates were 58.13~78.13% by the different washing processes, and there were significant differences between the washing processes (one-way ANOVA analysis and post-hoc Duncan test, p-value<0.05). The residues of azoxystrobin in crown daisy were safe levels from farm to fork after application with the critical good agricultural practice (cGAP) registered in Korea.

• Korean Journal of Environmental Agriculture
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• v.31 no.3
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• pp.248-254
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• 2012

BACKGROUND: In order to elucidate residual characteristics of difenoconazole and thiamethoxam by treatment to sweet persimmons for one year and to generate the data for the maximum residue limit (MRL) establishment for those pesticides in or on sweet persimmon. METHODS AND RESULTS: Systemic fungicide difenoconazole WP (10% a.i.) and systemic insecticide thiamethoxam WG (10% a.i.) were sprayed onto 12~25-years-old sweet persimmons according to its preharvest interval (PHI), respectively, and then fresh sweet persimmons were harvested at 0, 1, 3, 7, 14, 21 days after treatment from pesticide-sprayed plots at each 3 sites. The analytical methods were evaluated to limit of quantification, linearity, specificity, reproducibility and recoveries. The crop samples were extracted with acetone and performed dichloromethane partition process. The extracted samples of difenoconazole were analyzed by GC-ECD and the thiamethoxam extracted samples were analyzed by HPLC with good sensitivity and selectivity of the method. The average recoveries of difenoconazole ranged from 87.5 to 99.5% with the percentage of coefficient variation in the range 4.1~7.6% at three different spiking levels(0.02, 0.2 and 2.0 mg/kg). And the average recoveries of thiamethoxam and clothianidin ranged from 88.8 to 98.9% and 83.2 to 96.6% with the percentage of coefficient variation in the range 3.6~5.0% and 3.8~9.4% at three different spiking levels(0.02, 0.2 and 2.0 mg/kg), respectively. The residue amounts ranges of difenoconazole were 0.2~0.56 mg/kg and the residue amount was decreased below the MRL level, 1.0 mg/kg, after 1 day harvest. The residue amounts ranges of thiamethoxam were 0.08~0.28 mg/kg and the residue amount was decreased below the MRL level, 0.5 mg/kg, after 1 day harvest. And the residue amount of clothianidin was below then 0.03 mg/kg for only one test site of 14 and 28 day samples. CONCLUSION: As a result, the residual amounts of difenoconazole and thiamethoxam were not exceeded the MRL of established criteria for sweet persimmon. The biological half-lives of difenoconazole and thiamethoxam were 13.6, 19.4, 16.3 and 10.0, 15.3, 14.0 days at each three test sites, respectively.

• Journal of Food Hygiene and Safety
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• v.29 no.3
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• pp.234-240
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• 2014

Fluxapyroxad is classified as carboxamide fungicide that inhibits succinate dehydrogenase in complex II of mitochondrial respiratory chain, which results in inhibition of mycelial growth within the fungus target species. This study was carried out to assure the safety of fluxapyroxad residues in agricultural products by developing an official analytical method. A new, reliable analytical method was developed and validated using High Performance liquid Chromatograph-UV/visible detector (HPLC-UVD) for the determination of fluxapyroxad residues. The fluxapyroxad residues in samples were extracted with acetonitrile, partitioned with dichloromethane, and then purified with silica solid phase extraction (SPE) cartridge. Correlation coefficient($R^2$) of fluxapyroxad standard solution was 0.9999. The method was validated using apple, pear, peanut, pepper, hulled rice, potato, and soybean spiked with fluxapyroxad at 0.05 and 0.5 mg/kg. Average recoveries were 80.6~114.0% with relative standard deviation less than 10%, and limit of detection (LOD) and limit of quantification (LOQ) were 0.01 and 0.05 mg/kg, respectively. All validation parameters were followed with Codex guideline (CAC/GL 40). LC-MS (Liquid Chromatograph-Mass Spectrometer) was also applied to confirm the analytical method. Base on these results, this method was found to be appropriate fluxapyroxad residue determination and can be used as the official method of analysis.

• Journal of Food Hygiene and Safety
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• v.38 no.3
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• pp.112-122
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• 2023

We assessed the pesticide residues in the medicinal agricultural products distributed in Korea. Pesticide residues in 72 samples were analyzed using the QuECheRS method for 339 pesticides, using GC-MS/MS and LC-MS/MS. The pesticide residues were below the maximum residues limit (MRL) in 42 samples (58.3%); however, they exceeded the MRL in 5 samples (6.9%). These included 43 types of pesticides; 20 fungicides and 23 insecticides were detected 75 times and 58 times, respectively. Tebuconazole and carbendazim were the most detected fungicides, each 11 times. The levels of acetamiprid, cadusafos, chlorpyrifos, flubendiamide, fluopyram, and triazophos exceeded the MRL in Gogi berry, Omija, and Reishi mushroom. All of them were positive list system (PLS) items that lacked pesticide residue standards. Therefore, authorities should monitor the distributed medicinal agricultural products.

• Journal of Food Hygiene and Safety
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• v.34 no.4
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• pp.340-347
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• 2019

We performed a safety survey on residual pesticides in dried agricultural products. A total of 110 samples of dried agricultural products distributed in Gyeonggi-do were analyzed for 263 pesticides according to multi class pesiticide multiresidue method. Ten types of pesticides were detected in 10 samples. Chlorpyrifos was detected in Ricinus communis leaves, chlorpyrifos, hexaconazole, pyridalyl in Chwinamul (wild aster), diniconazole, isoprothiolane, lufenuron in radish leaves, hexaconazole in Cirsium setidens (Korean thistle), bifenthrin, and chlorothalonil, boscalid, and pyraclostrobin in pepper leaves. The detection rate of pesticides was 9.1%, and among these samples, one was detected over Maximum Residue Limits (MRLs). In the validation study, the values of limit of detection (LOD), limit of quantitation (LOQ), coefficient of determination ($R^2$) and recovery were in the range of 0.002~0.027 mg/kg, 0.006~0.083 mg/kg, 0.9964~1.0000 and 74.8~118.9%, respectively. The Positive List System (PLS) was newly introduced as part of the safety management of residual pesticide in agricultural products in Korea in 2019. With the application of the PLS, if the MRL is not established, 0.01 mg/kg limit is applied uniformly. In spite, these of strengthened residue limits, the MRLs of dried agricultural products are still insufficient. Therefore, this study could be utilized as basic data for the setting of proper MRLs.