• Journal of Applied Biological Chemistry
• /
• 제60권4호
• /
• pp.339-342
• /
• 2017

Residual endosulfan in an agricultural environment has been reported, although endosulfan was listed to persistent organic pollutants and banned. To produce the safe crop from endosulfan residue risk, the plant uptake potential of endosulfan from soil to crop should be studied. In here, the plant uptake potentials of endosulfan in various crops were surveyed and ranged from 0.002-4.460. And the bioconcentration factors (BCF) of total endosulfan in carrot and spinach were calculated from the pot experiment. The BCFs in carrot and spinach were 0.285 and 0.040-0.047 respectively. Endosulfan sulfate was contributed to over 42.8% of the crop residue as a major contributor among the three endosulfan congeners in both of carrot and spinach.

• The Korean Journal of Pesticide Science
• /
• 제15권4호
• /
• pp.389-400
• /
• 2011

A high-performance liquid chromatographic (HPLC) method was developed to determine residues of phenothrin and silafluofen, known as synthetic pyrethroids, in agricultural commodities. Insecticide residues were extracted with acetone from representative samples of four crops which comprised rice, apple, pepper and cabbage. The extract was purified serially by liquid-liquid partition and Florisil column chromatography. For rice and pepper samples, acetonitrile/n-hexane partition was additionally adopted to remove nonpolar interferences. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate two phenothrin isomers and silafluofen from sample co-extractives. Intact parent compounds were sensitively detected by ultraviolet absorption at 226 nm. Recovery experiment at the quantitation limit validated that the proposed method could apparently determine phenothrin and silafluofen residues at 0.02 and 0.01 mg/kg, respectively. Mean recoveries of phenothrin and silafluofen from four crop samples fortified at three levels in triplicate were in the range of 82.4~109.8% and 83.7~109.8%, respectively. Relative standard deviations of the analytical method were all less than 10%, irrespective of crop types and spiking levels. A selected-ion monitoring (SIM) LC/mass spectrometry (MS) with electrospray ionization was provided to confirm the suspected residue of phenothrin, even though no sufficient ionization of silafluofen was obtained. Both phenothrin and silafluofen could be successfully confirmed by gas chromatography/MS SIM with electron impact at 70 eV. The proposed method is sensitive, repeatable and rapid enough to apply to officially routine inspection of agricultural products.

• Korean Journal of Environmental Agriculture
• /
• 제40권4호
• /
• pp.260-269
• /
• 2021

BACKGROUND: Diquat dibromide is a fast-acting nonselective herbicide and plant growth regulator. In this study, in order to understand the possibility of unintentional pesticide contamination in the following crops, the phytotoxicity and transition of diquat dibromide residue in soil into the following crops such as pepper, radish, lettuce and corn have been assessed through phytotoxicity trial and residual evaluation in the unintentional contamination of the higher residual diquat dibromide. METHODS AND RESULTS: The pepper, radish, lettuce and corn were cultivated in the sandy soil and loam soil where the 35 mg/kg and 90 mg/kg diquat dibromide were applied, respectively. Mild growth inhibition symptoms were observed in radish, lettuce and corn crops at the 90 mg/kg- diquat dibromide treatment on the 30 day of cultivation. Diquat dibromide was analyzed using liquid chromatography QTRAP (LC-MS/MS). The recovery rates of diquat dibromide from soil and crop were determined within range from 89.1 to 116.4% with relative standard deviation less than 14.7%. Diquat dibromide residues in soil were found to be 23.90-30.22 and 69.59-82.57 mg/kg from the 35 mg/kg and 90 mg/kg of diquat dibromide-treated soil, respectively after 30 days of crop cultivation. This result implicates that diquat dibromide did not convert to metabolites and remained mostly in the soil, even though it was partially decomposed during crop cultivation. In addition, the diquat dibromide in pepper and radish that were grown for 47 days, and lettuce and corn that were cultivated for 30 days were detected to be 0.01 mg/kg or less in the sandy loam and loam soil where the 90 mg/kg diquat dibromide was applied. CONCLUSION(S): Diquat dibromide did not cause severe phytotoxicity in the following crops as well as it did not uptake and distribute to the following crops, even though it was considered to be residual in the soil.

• The Korean Journal of Pesticide Science
• /
• 제16권4호
• /
• pp.328-335
• /
• 2012

In order to use in the classification of minor crop for the mutual application of safe use guideline, it was investigated the residue property of fungicide dimethomorph and pyraclostrobin in green onion, a stem-crop. After pesticides were applied 2 times with 1 week interval in that day of harvest, 3 days, 7 days, 10 days and 14 days before harvest, a green onion was harvested. The residue of dimethomorph in a green onion was 26.31 and 39.08 mg/kg in that day of harvest, however, in according to elapse time, it was reduced to 6.86 and 9.34 mg/kg in 14 days before harvest. In case of pyraclostrobin, it was also reduced from 13.46 and 39.08 mg/kg to 3.57 and 5.21 mg/kg. Based on the residue in that day of harvest, the deposit of spray solution in a green onion was calculated. The deposit of spray solution of dimethomorph was 274.35~345.84 mL/kg, in case of pyraclostrobin, it was calculated 213.65~343.33 mL/kg. When the amount of the deposit of both pesticides was compared in a green onion, it was so similar. On the other hand, it was estimated the predicted dissipation curve of pesticides in the green onion during cultivation. The half-life of dimethomorph was 6.95~7.45 days, in case of pyraclostrobin, 7.15~7.45 days. When both pesticides were compared with the residue property, the deposit of spray solution and half-life of dissipation were so similar.

• Korean Journal of Agricultural Science
• /
• 제32권2호
• /
• pp.215-221
• /
• 2005

The residual study of pesticide has been used in various areas, such as food safety, environmental protection, establishment of tolerance, and explaining the pathway and reaction mode of pesticides, and its importance was expected to increase further more. The aspect of food safety, the pesticide residue survey have been practiced at many organizations, but there were no verification of analytical results at present. In this experiment, we focused on instrumental stability, including response of each instrument and the recovery ratio of each organization's method. As samples for this experiment, we prepared cucumber and sesame, and chose 4 pesticides (bifenthrin, chlorpyrifos, diazinon, and ethoprophos), which were mostly detected from pesticide residue survey and widely used for each crop. The standard deviation of peak areas in the chromatogram of each pesticide were under 1.212 %, so it showed that most instruments were stable. The relationship of recovery ratio of each organization were over 0.996 for every pesticide and each organization. Finally, the analytical results for pesticide residue from each participated organization were not statically significant and we could put confidence in the result from each organization.

• Korean Journal of Environmental Agriculture
• /
• 제41권4호
• /
• pp.355-364
• /
• 2022

BACKGROUND: Pre-harvest interval and decline pattern of thiamethoxam were determined in kiwifruit using liquid chromatography-tandem mass spectrometry (LCMS/MS). The study was carried out to propose import tolerance using OECD maximum residue limit (MRL) calculator for the export promotion of kiwifruit to Taiwan. METHODS AND RESULTS: The thiamethoxam residue in kiwifruit was determined by using the LC-TriQ-MS/MS with the analytical process to set up the import tolerance under greenhouse conditions for Taiwan. Excellent linearity was observed for all of the analytes with a determination coefficient (R²)≥0.99. The limit of quantification was determined to be 0.01 mg/kg for both thiamethoxam and clothianidin in kiwifruit. Linearity was determined from the co-efficient of determinants (R²) obtained from the seven-point calibration curve. The standard calibration curve showed as follows; 1) Site 1 (Gimje): y = 944,406X + 1,583 (R²=0.9995), 2) Site 2 (Goheung): y = 1,356,205X + 934 (R²=0.9983), and 3) Site 3 (Jangheung): y = 1,239,937X - 3,090 (R²=0.9908). The residue of thiamethoxam in the kiwifruit for three decline trials showed the range of 0.35 to 0.56 mg/kg in site 1 (Gimje), 0.24 to 0.55 mg/kg in site 2 (Goheung), and 0.28 to 0.42 mg/kg in site 3 (Jangheung), respectively. However, clothianidin was not detected in all of the treatments. The maximum residual amounts (decline) in the samples, sprayed according to the safe-use standard for thiamethoxam 10% WG in kiwifruit (30 days before harvest, 3 sprays every 7 days) were 0.56 mg/kg in site 1, 0.55 mg/kg in site 2, and 0.42 mg/kg in site 3, respectively. CONCLUSION(S): The import tolerance (IT) of thiamethoxam for kiwifruit may be proposed to be 0.9 mg/kg by using the OECD MRL calculator.

• Journal of Korean Society for Atmospheric Environment
• /
• 제31권1호
• /
• pp.63-71
• /
• 2015

The gaseous and particulate emissions from agricultural crop residues burning were investigated. The test residues included white soybean stem, pepper stem, apple branch, peach branch, pear branch, grape branch, sesame stem, perilla stem, and barley stem. Particulate emissions were dominated by fine particles (< $0.1{\mu}m$ in size). The highest $PM_{2.5}$ Emission factors were from barley stems (35.2 g/kg), and the lowest from pepper stems (7.9 g/kg). Emission factors for CO, NO, and VOCs were 146~305 g/kg, 4.94~15.02 g/kg, 27.4~353.3 g/kg, respectively. Benzene played an important role in VOCs emissions from biomass burning.

• Korean Journal of Environmental Agriculture
• /
• 제14권1호
• /
• pp.23-27
• /
• 1995

The cross-reactivities of antibody derived from rabbit immunized with metalaxyl-HSA conjugate were identified to 44% and 28% for metalaxyl acid and metolachlor respectively. The detection range of metalaxyl in competitive ELISA was 5 ppb to 5 ppm. The recoveries of metalaxyl in ELISA for 6 crops; potato, sesame, pepper, cabbage, cucumber and onion was ranged 77.5-103.6%. In this test, CV% were calculated below 10% except for sesame sample as shown 21.5%.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• 제51권1호
• /
• pp.101-106
• /
• 2006

Common thistle contains water-soluble substances that are phytotoxic to neighboring plant species. A series of aqueous extracts from leaves, stems, roots and flowers of common thistle (Cirsium pendulum Fisch.) were assayed against alfalfa (Medicago sativa) seedlings to determine their allelopathy, and the results showed highest inhibition in the extracts from flowers and leaves, and followed by stems, and roots. The extracts at 40 g dry tissue $L^{-1}(g\;L^{-1})$ applied on filter paper in a Petri-dish significantly inhibited root growth of test plant by 87%. Methanol extracts at 100 g $L^{-1}$ from leaves inhibited root growth of alfalfa and barnyardgrass (Echinochloa crus-galli) by 89 and 98%, respectively. Hexane and ethylacetate fractions of common thistle reduced alfalfa root growth more than did butanol and water fractions. Incorporation into soil with the leaf residues at $100g\;kg^{-1}$ inhibited shoot fresh weights of barnyardgrass and eclipta (Eclipta prostrate) by 88 and 58%, respectively, showing higher sensitivity in grass species. These results suggest that common thistle plants had allelopathic potential for eco-friendly vegetation management, and that especially their activities were differently exhibited depending on plant part.

• Korean Journal of Soil Science and Fertilizer
• /
• 제33권2호
• /
• pp.61-70
• /
• 2000

Soil erosion in the hilly and mountainous uplands in the Daekwanryong area, Kangwon-Do, were investigated through a field plot experiment. The plot size was 15m long and 2.5m wide with the average slope of 12.5 percents. Soil erodibility factor (K), surface coverage (SC), soil aggregate percentage and wind erodibility (I) were evaluated in the mountainous soils under different management practices for corn and potato cultivations. Soil erodibility factor (K) was greater in upper part than in lower part of the plots. Surface coverage (SC) values ranged from 0.01 to 0.84 depending on the amounts of crop residues. Soils having a greater crop residue in surface were less subjected to soil erosion. SC values after corn harvest were 0.4 to 0.8, while those after potato harvest were 0.4 to 0.5, indicating potato might be better than corn for erosion control. Soil aggregate percentages of the experimental plots ranged from 49.7 to 79.8%. Those were higher in potato-cultivated plots with higher surface coverage, organic fertilizer treatment and contour tillage. Soil aggregate percentage of potato-cultivated plots was significantly correlated to crop residue coverage after harvest. The dried soil aggregate percentage, showing the ranges of 26.4 to 56.4%, were higher in the plots with the increased crop residue incorporation. Wind erodibility (I) of the soil was decreased with increasing surface coverage. When soil had 26.4% of the dried aggregate percentage, wind erodibility was estimated to be $183Mgha^{-1}$ which was equivalent to soil loss of $0.5Mg\ha^{-1}day^{-1}$.