• Korean Journal of Environmental Agriculture
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• v.32 no.1
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• pp.84-93
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• 2013

BACKGROUND: This study was carried out to investigate the residual characteristics of insecticides used for Oriental Tobacco Budworm control and to establish the recommended pre-harvest residue limit leading to contribution in safety of paprika production. METHODS AND RESULTS: The recommended Pre-Harvest Residue Limits (PHRLs) of insecticides during cultivation of paprika were calculated from residue analyses of insecticides in fruits 1, 3, 5, 7, 10, 12, 15, 18 and 21 days after treatment. Paprika samples were extracted with QuEChERS method and cleaned-up with amino propyl SPE cartridge and PSA, and insecticide residues were analyzed either by HPLC/DAD or GLC/ECD. The limits of detection were 0.01 mg/kg for 5 insecticides. Average recoveries were $81.3{\pm}1.62%$-$98.3{\pm}1.58%$ of 5 insecticides at fortification levels of 0.1 and 0.5 mg/kg. The biological half-lives of the insecticides were 8.5 days for bifenthrin, 11.8 days for chlorantraniliprole, 16.8 days for chlorfenapyr, 7.1 days for lamda-cyhalothrin and 31.3 days for methoxyfenozide at recommended dosage, respectively. CONCLUSION(S): The pre-harvest residue limits for 10 days before harvest were recommended 1.05 mg/kg, 1.41 mg/kg, 0.93 mg/kg, 2.06 mg/kg and 1.08 mg/kg as bifenthrin, chlorantraniliprole, chlorfenapyr, lamda-cyhalothrin and methoxyfenozide, respectively. This study can provide good practical measures to produce safe paprika fruit by prevention of products from exceeding of MRLs at pre-harvest stage.

• Korean Journal of Environmental Agriculture
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• v.42 no.1
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• pp.21-27
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• 2023

Pre-harvest residue limits (PHRLs) have been proposed as criteria for a proactive role to exceed the maximum residue limit (MRL) of pesticides in agricultural products at harvest. However, PHRL numbers are significantly less than those of established MRLs. This study was performed to determine the dissipation constants and residual concentrations of lufenuron after application on crown daisy and chamnamul under green house conditions. Two residue field trials for each crown daisy and chamnamul were selected to consider a different geographical site at least 20 km far from one another. The pesticide was treated according to critical GAP. After samples were sprayed with lufenuron, they were collected at 0, 1, 3, 5, 7, 10, and 14 days and analyzed using HPLC-DAD. The mean recoveries of crown daisy and chamnamul were within the range of 70-120% with below 20% coefficient variation, which is within the acceptable limits specified by the manual of pre-harvest residue study for pesticides (MFDS, 2014). The biological half-lives in field I and field II were 7.0 and 4.6 days for crown daisy and 2.7 and 2.8 days for chamnamul, respectively. The lower bounds of 95% confidence intervals of dissipation rate constants of lufenuron in crown daisy were determined to be 0.0692 and 0.1298 for field I and field II, respectively, and in chamnamul were 0.2067 for both field I and field II. After applying lufenuron 5% EC, the lufenuron residues on crown daisy and chamnamul at the pre-harvest intervals (14 days for crown daisy and 7 days for chamnamul) were below the safe levels. The dissipation rates of lufenuron in crown daisy and chamnamul were evaluated for similarities with leafy vegetables based on a 95% confidence interval.

• Agribusiness and Information Management
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• v.3 no.1
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• pp.11-22
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• 2011

This study describes the development of a web-based system that collects all data generated in the research conducted to set pre-harvest residue limits (PHRLs) for agricultural product safety control. These data, including concentrations of pesticide residues, limit of detection, limit of quantitation, recoveries, weather charts, and growth rates, are incorporated into a database, a regression analysis of the data is performed using statistical techniques, and the PHRL for an agricultural product is automatically computed. The development and establishment of this system increased the efficiency and improved the reliability of the research in this area by standardizing the data and maintaining its accuracy without temporal or spatial limitations. The system permits automatic computation of the PHRL and a quick review of the goodness of fit of the regression model. By building and analyzing a database, it also allows data accumulated over the last 10 years to be utilized.

• 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.

• Korean Journal of Environmental Agriculture
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• v.37 no.1
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• pp.41-48
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• 2018

BACKGROUND: This study was performed to calculate the biological half-lives and regression coefficient of bistrifluron and cyenopyrafen dissipation in peach and to estimate the Pre-Harvest Residue Limits (PHRLs). METHODS AND RESULTS: The bistrifluron and cyenopyrafen were prepared on the basis of good agricultural practice for peach and treated with a single application. Peaches were harvested at 0, 1, 3, 5, 7, 10 and 14 days after application, prepared for analysis, and analyzed by HPLC-DAD. The limits of quantitation (LOQ) of bistifluron and cyenopyrafen were 0.02 mg/kg and 0.04 mg/kg, respectively. The recoveries of bistrifluron and cyenopyrafen were 99.5~108.7% and 88.4~98.9% at two different concentration levels. The biological half-lives of field I (Sejong) and field II (Pyeongtaek) were 6.1 and 7.0 days for bistifluron, and 6.3 and 7.0 days for cyenopyrafen, respectively. The 95% confidence intervals of dissipation rate constants of bistrifluron in peach were 0.0805~0.1457 and 0.0577~0.1417 for field I and field II, respectively, and those of cyenopyrafen were 0.0911~0.1278 and 0.0576~0.1417, respectively. CONCLUSION: Residue dissipation of bistrifluron and cyenopyrafen in peach were similar to that of correction to sample weight difference during the harvest periods. This study suggests that residue dissipation rate would be helpful to set the PHRLs that protect public health.

• Korean Journal of Environmental Agriculture
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• v.34 no.4
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• pp.328-335
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• 2015

BACKGROUND: The present investigation was aimed to predict the pre-harvest residue limits (PHRLs) of the fluopicolide and metrafenone on cherry tomato and to estimate their half-life and characteristics of the residues.METHODS AND RESULTS: Pesticides were treated once on cherry tomato in field 1 and 2 under the standard application rate. The samples were collected 7 times at the end of 0(2 hours after pesticides spaying), 1, 2, 3, 5, 7 and 10 days before harvest. Residues of fluopicolide and metrafenone were analyzed by the LC-MS/MS. In this study, the method limit of quantification (MLOQ) for both fluopicolide and metrafenone in cherry tomato was found to be 0.005 mg kg-1. Their recovery levels were 92.7∼94.8% and 82.6∼88.0%, shown with coefficient of variation of less than 10%. Half-life of fluopicolide and metrafenone in field 1 and 2 were found to be 15.0 days and 12.8 days, 18.9 days and 21.5 days, respectively.CONCLUSION: Based on the results, this study shows the level of PHRL on cherry tomato is 0.27 mg/kg for fluopicolide and 2.29 mg/kg for metrafenone at 10 days before harvesting. The present study indicates the residues of both pesticides on cherry tomato will be below maximum residue limit (MRL) at harvest.

• Journal of Applied Biological Chemistry
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• v.65 no.3
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• pp.173-181
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• 2022

This study was carried out to investigate the residual characteristics of flubendiamide in kale to establish pre-harvest residue limits (PHRL) and the removal efficiency according to the washing solvent and method. Field tests were conducted at two different greenhouses, field 1 (Anseong-si, Gyeonggi-do) and field 2 (Incheon-si, Gyeonggi-do). According to the safe use guidelines kale was sprayed with flubendiamide twice every 10 days and harvested 0 (after 2 h), 1, 2, 3, 5, 7 and 10 days after the final application. The biological half-live of flubendiamide in kale was calculated based on dissipation curves of the pesticide in samples analyzed by liquid chromatography coupled with tandem mass spectrometry. In the analysis, method limits of quantitation (MLOQ) were 0.01 mg/kg, and recoveries performed with two different fortification levels of 10 MLOQ and maximum residue limit (0.7 mg/kg) were 104.2±3.6 and 101.9±10.2%, respectively. The dissipation rate constant of flubendiamide in kales were 0.2437 at field 1 and 0.1981 at field 2. PHRL calculation equations obtained using the dissipation constants estimated as follows: if the residual concentration of flubendiamide in kale on 10 days before harvest is less than 8.0 mg/kg, the residual concentration on the harvest would be under MRL. The removal of flubendiamide from kale was the greatest when it was washed with vinegar (39.8%), followed by baking soda (31.7%), calcium powder (30.2%), neutral detergent (27.2%), and tap water (15.9%). The results of this study would be useful for both farmers and consumers to produce or consume safe agricultural products.

• Korean Journal of Environmental Agriculture
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• v.31 no.3
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• pp.271-276
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• 2012

BACKGROUND: It is hard to control the agricultural products exceeding MRL (maximum residue limit) before forwarding. Therefore, NAQS (National Agricultural Products Quality Management Service, South Korea) established PHRL (pre-harvest residue limit) on agricultural products during their cultivation periods. This study was performed to set the PHRLs of peach during cultivation period, and also to estimate biological half-lives for residues of clothianidin and fluquinconazole. METHODS AND RESULTS: Two groups of peach were treated under Korean GAP (Good Agricultural Practices) with application time, single and triple treatments. Sample was collected over 14days (each after 0, 2, 4, 6, 8, 10, 12, 14 days. 8times), and clothianidin and fluquinconazole were analyzed by HPLC/DAD and GC/ECD, respectively. CONCLUSION: The biological half-life of clothianidin in single treatment and triple treatment was 5.2days and 7.0days. That of fluquinconazole was also 3.9days and 4.1days, respectively. The PHRL of peach on 10days before harvest was 1.4 mg/kg in clothianidin and 1.8 mg/kg in fluquinconazole.

• Journal of Applied Biological Chemistry
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• v.63 no.3
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• pp.267-274
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• 2020

The dissipation characteristics and kinetics of fungicide mandipropamid and insecticide thiamethoxam in lettuce under greenhouse conditions were investigated at three different lettuce-growing fields for estimating the pre-harvest residue limits (PHRLs). The analytical methods were fully validated for the quantitation of pesticide residues using High-Performance Liquid Chromatography-Photo Diode Array detector or Ultraviolet-Visible Detector and applied to real samples. The lettuces suitable for shipment were harvested during 10 days including pre-harvest interval after treatment at the recommended dose by safe-use guidelines. The initial mean residues in different fields were 6.68-17.87 and 4.96-8.31 mg/kg for mandipropamid and thiamethoxam, respectively, which decreased to 16-54 and 14-44% in 10 days. The clothianidin, a metabolite of thiamethoxam, was detected in <0.02 to 0.37 mg/kg. The dissipation of both pesticides followed first-order kinetics over a period of 10 days after application. Based on the residue data, the mean dissipation rate constant (λ) and biological half-lives (T_1/2) were estimated to be -0.1060 and 6.5 days of mandipropamid and -0.1236 and 5.6 days of thiamethoxam. The PHRLs for lettuce on the 10th and 5th day before harvesting were calculated to be 63.24 and 43.56 mg/kg for mandipropamid, and 44.66 and 25.88 mg/kg for thiamethoxam, with -0.0746 and -0.1091 of the upper 95% confidence intervals of dissipation rate constant, respectively. This work would be useful as guidance for adjusting the shipment date and contribute to stabilizing the income of farmers in Korea.

• Korean Journal of Environmental Agriculture
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• v.40 no.2
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• pp.118-126
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• 2021

BACKGROUND: It is very important to monitor the residual characteristics of pesticides in pre-harvest fresh ginseng to ensure consumer safety. METHODS AND RESULTS: Forty-eight fresh ginseng samples were collected from 8 ginseng-growing fields 10 days before harvest and pesticide residues in fresh ginseng with and without rhizome (head of ginseng) and rhizome were analyzed for 320 pesticides by using GC-MS/MS and LC-MS/MS. As a result of the pesticide residue analysis, the number of pesticides detected from the fresh ginseng with rhizome, that without rhizome and rhizome were 26, 25, and 40, respectively, indicating that high number of pesticides found in rhizome, compared with the other parts. Pyraclostrobin was detected with the highest frequency in all samples, reaching to 21.2% in fresh ginseng with rhizome, 16.8% in that without rhizome, and 14.8% in rhizome. CONCLUSION: The residue levels of pesticides detected did not exceed their maximum residue limits, in spite of residual data in fresh ginseng before harvest. The amounts of the estimated daily intakes of all the detected pesticides were found to be from 0.018 to 1.818% of their acceptable daily intakes, indicating that concentrations of pesticides detected from fresh ginseng with and without rhizome collected before harvest do not pose the immediate health risks.