• Title, Summary, Keyword: residues

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Persistence and Dislodgeable Residues of Chlorpyrifos and Procymidone in Lettuce Leaves under Greenhouse Condition (상추의 생산단계별 Chlorpyrifos 및 Procymidone의 잔류허용기준 설정)

  • Kim, Young-Sook;Park, Ju-Hwang;Park, Jong-Woo;Lee, Young-Deuk;Lee, Kyu-Seung;Kim, Jang-Eok
    • Korean Journal of Environmental Agriculture
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    • v.21 no.2
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    • pp.149-155
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    • 2002
  • Two pesticides commonly used for lettuce cultivation including chlorpyrifos and procymidone were subjected to a field residue trial to ensure safety of terminal residues in the harvest. After pesticides were applied at standard and double rates in a foliar spray, leaf persistence of their residues was investigated far 10 days prior to harvest. Even though far exceeded the tolerances, initial leaf residues were rapidly dissipated with time and remained only 0.4$\sim$7.2% of the residues in the harvest. As well fitted by the first-order kinetics, biological half-lives of the pesticide residues in lettuce leaves ranged 1.2$\sim$2.6 days. Slow dissipation of the residues in the harvest was observed during storage at room temperature and 4$^{\circ}C$ for 7 days. Portions of dislodgeable residues which resided in detergent washings decreased as time elapsed. Patterns in dissipation and distribution of dislodgeable residues were not largely affected by the application rate of pesticides. It is concluded that timing of pesticide application, that is, pre-harvest interval would be the first factor to determine the terminal residue level in edible portions of lettuce.

Behaviour of the soil residues of the herbicide quinclorac in the micro-ecosystem (pot) (Micro-ecosystem(pot)중 제초제 quinclorac 토양잔류물의 행적)

  • Ahn, Ki-Chang;Kyung, Kee-Sung;Lee, Jae-Koo
    • The Korean Journal of Pesticide Science
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    • v.2 no.3
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    • pp.96-106
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    • 1998
  • Rice plants were grown for 42 days in the specially made micro-ecosystem(pot) containing two different soils treated with fresh and 60-day-aged residues of [$^{14}C$]quinclorac, respectively, to elucidate the behaviour of the herbicide quinclorac residues in the soils. Amounts of $^{14}CO_{2}$ evolved from two soils treated with different residues with and without vegetation were all less than 2.2% of the total $^{14}C$, indicating that there was little microbial degradation of quinclorac in soil. $^{14}C$-Radioactivity absorbed and translocated into rice plants from soil A and B containing fresh quinclorac residues was 8.4 and 24.2%, respectively, of the originally applied $^{14}C$, while 5.5 and 17.7%, in aged residue soils. These results indicate that larger amounts of $^{14}C$ were absorbed by rice plants from soil B with less organic matter and clay than soil A, and the uptake of [$^{14}C$]quinclorac and its degradation products decreased with aging in soil. After 42 days of rice growing, 84.5 and 61.8% of the $^{14}C$ applied freshly to soil A and B, respectively, remained in soil, whereas, in the case of aged soils, 86.3 and 67.7% of the $^{14}C$ applied did. Meanwhile, without vegetation, more than 98.3% of the $^{14}C$ applied, in both fresh and aged residues, remained in soil, suggesting that quinclorac was relatively persistent chemically and microbiologically. Most of the non-extractable soil-bound residues of [$^{14}C$]quinclorac were incorporated into the organic matter and largely distributed in the fulvic acid portion.

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Development and Validation of an Analytical Method for Tridemorph Determination in Tea Samples by Liquid Chromatograph-Electrospray Ionization-Tandem Mass Spectrometry

  • Do, Jung-Ah;Park, Hyejin;Kwon, Ji-Eun;Cho, Yoon-Jae;Chang, Moon-Ik;Oh, Jae-Ho;Hwang, In-Gyun
    • Journal of Food Hygiene and Safety
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    • v.29 no.4
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    • pp.292-298
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    • 2014
  • Tridemorph is a systemic morpholine fungicide for crops. The objective of this study was to develop reliable and sensitive analytical method for determination of tridemorph residues in tea samples for ensuring the food safety. Tridemorph residues in samples were extracted with acetonitrile after hydration, partitioned with saline water, and then purified using an aminopropyl ($NH_2$) SPE cartridge. The purified samples were detected and quantified using LC-ESI-MS/MS. The linear detection limits for tridemorph ranged from 0.02 to $1.0mgL^{-1}$ with a correlation coefficient of 0.9999. The method was validated using tea samples spiked with tridemorph at different concentration levels (0.02 and $0.05{\mu}gmL^{-1}$). The average recovery ranged between 75.0 and 84.7% with relative standard deviations less than 10%. The LOD and LOQ were 0.01 and $0.02mgL^{-1}$, respectively. The developed method was applied successfully to the identification of tridemorph in real tea samples obtained from different sources, and tridemorph was not detected in any of the samples. The results show that the developed analytical method is accurate and suitable for tridemorph determination in tea samples.

Development and validation of an analytical method for pyrimisulfan determination in agricultural commodities by LC-MS/MS (LC-MS/MS를 이용한 농산물 중 pyrimisulfan 잔류량 분석법 개발 및 확인)

  • Do, Jung-Ah;Lee, Mi-Young;Cho, Yoon-Jae;Kang, Iil-Hyun;Kwon, Kisung;Oh, Jae-Ho
    • Analytical Science and Technology
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    • v.26 no.2
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    • pp.154-163
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    • 2013
  • The maximum residue limits of pyrimisulfan is set as 0.05 mg/kg in rice in 2011, so very reliable and sensitive analytical method for pyrimisulfan residues is required for ensuring the food safety of pyrimisulfan residues in agricultural products. In this study, a rapid and sensitive analytical method was developed and validated using liquid chromatography electrospray ionization tandem mass spectrometry (LC-MS/MS) for the determination of herbicide pyrimisulfan residues in agricultural products. Average recoveries of pyrimisulfan ranged from 88.7 to 99.3% at the spiked level of 0.005 mg/kg and from 90.1 to 94.2% at the spiked level of 0.05 mg/kg, while the relative standard deviation was less than 10%. Linear range of pyrimisulfan was between 0.01~1.0 ${\mu}g/mL$ with the correlation coefficient ($r^2$) 0.999 and limit of quantification was 0.005 mg/kg. The results of method validation were satisfied Codex guideline. The results revealed that the developed and validated analytical method is possible for pyrimisulfan determination in agricultural product samples and will be used as an official analytical method.

Development and Validation of an Analytical Method for the Insecticide Sulfoxaflor in Agricultural Commodities using HPLC-UVD (HPLC-UVD를 이용한 농산물 중 살충제 sulfoxaflor의 시험법 개발 및 검증)

  • Do, Jung-Ah;Lee, Mi-Young;Park, Hyejin;Kwon, Ji-Eun;Jang, Hyojin;Cho, Yoon-Jae;Kang, Il-Hyun;Lee, Sang-Mok;Chang, Moon-Ik;Oh, Jae-Ho;Hwang, In-Gyun
    • Korean Journal of Food Science and Technology
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    • v.45 no.2
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    • pp.148-155
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    • 2013
  • Sulfoxaflor is a new active ingredient within the sulfoximine insecticide class that acts via a unique interaction with the nicotinic receptor. The MRLs (maximun residue limit) of sulfoxaflor in apple and pear are set at 0.4 mg/kg and that in pepper is set at 0.5 mg/kg. The purpose of this study was to develop an analytical method for the determination of sulfoxaflor residues in agricultural commodities using HPLC-UVD and LC-MS. The analysis of sulfoxaflor was performed by reverse phase-HPLC using an UV detector. Acetone and methanol were used for the extraction and aminopropyl ($NH_2$) cartridge was used for the clean-up in the samples. Recovery experiments were conducted on 7 representative agricultural products to validate the analytical method. The recoveries of the proposed method ranged from 82.8% to 108.2% and relative standard deviations were less than 10%. Finally, LC-MS with selected ion monitoring was also applied to confirm the suspected residues of sulfoxaflor in agricultural commodities.

Effects of Replacing Nonfiber Carbohydrates with Nonforage Detergent Fiber from Cassava Residues on Performance of Dairy Cows in the Tropics

  • Kanjanapruthipong, J.;Buatong, N.
    • Asian-Australasian Journal of Animal Sciences
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    • v.17 no.7
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    • pp.967-972
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    • 2004
  • Four Holstein$\times$Indigenous cows with ruminal canulas were used in a 4$\times$4 Latin square design with 28 d periods to determine the effect of replacing nonforage fiber source (NFFS) from cassava residues for non-fiber carbohydrates (NFC) on ruminal fermentation characteristics and milk production. Dietary treatments contained 17% forage neutral detergent fiber (FNDF) from corn silage and 0, 3, 6 and 9% nonforage NDF from cassava residues and 11% nonforage NDF from other NFFS, so that levels of nonforage NDF were 11, 14, 17 and 20% dry matter (DM). Intakes of DM and net energy for lactation, average daily gain and milk fat percentage were not different (p>0.05). Ruminal pH, ammonia concentrations, acetate to propionate ratios, 24 h in sacco fiber digestibility significantly increased with increasing contents of nonforage NDF from cassava residues. Concentrations of VFA, urinary excretion of purine derivatives, milk protein percentage, production of milk and 4% FCM significantly decreased. These results suggest that NFC in diets is one of the limiting factors affecting productivity of dairy cows in the tropics and thus NFFS is better used as partial replacements for FNDF.

Functional identification of protein phosphatase 1-binding consensus residues in NBCe1-B

  • Lee, Kyu Pil;Kim, Hyun Jin;Yang, Dongki
    • The Korean Journal of Physiology and Pharmacology
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    • v.22 no.1
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    • pp.91-99
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    • 2018
  • Protein phosphatase 1 (PP1) is involved in various signal transduction mechanisms as an extensive regulator. The PP1 catalytic subunit (PP1c) recognizes and binds to PP1-binding consensus residues (FxxR/KxR/K) in NBCe1-B. Consequently, we focused on identifying the function of the PP1-binding consensus residue, $^{922}FMDRLK^{927}$, in NBCe1-B. Using site-directed mutagenesis and co-immunoprecipitation assays, we revealed that in cases where the residues were substituted (F922A, R925A, and K927A) or deleted (deletion of amino acids 922-927), NBCe1-B mutants inhibited PP1 binding to NBCe1-B. Additionally, by recording the intracellular pH, we found that PP1-binding consensus residues in NBCe1-B were not only critical for NBCe1-B activity, but also relevant to its surface expression level. Therefore, we reported that NBCe1-B, as a substrate of PP1, contains these residues in the C-terminal region and that the direct interaction between NBCe1-B and PP1 is functionally critical in controlling the regulation of the ${HCO_3}^-$ transport. These results suggested that like IRBIT, PP1 was another novel regulator of ${HCO_3}^-$ secretion in several types of epithelia.

Isolation of Ethanol-tolerant Strains of Yeast in Relation to Their Tolerant Mechanism (에탄올 내성 효모의 선별과 그의 에탄올 내성 기작)

  • 지계숙;박소영;이지나;이영하;민경희
    • Korean Journal of Microbiology
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    • v.29 no.2
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    • pp.136-142
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    • 1991
  • The selection of ethanol-tolerant strains was applied to enrichment culture of YPD broth medium containing various concentrations of ethanol. Isolates were identified to be Saccharomyces cerevisiae, the others as S. dairensis, S. exiguus, S. telluris, Saccharomycodes ludwigii, Schwanniomyces occidentalis var. occidentalis and Zygosaccharomyces florentinus. Among isolates S. cerevisiae YO-1 was screened as having the highest ethanol tolerance and produced 18% (v/v) ethanol after 4 days fermentation. The change of fatty-acyl residues represents that a progressive decrease in fatty-acyl unsaturation and a proportional increase in saturation in phospholipids of yeast cells during fermentation affected the yeast viability. Supplementation ethanol to the cultures led to an increase of unsaturated fatty-acyl residues, especially $C_{16}$ or $C_{18}$ residues, along with a decrease in the proportion of saturated residues in cellular phospholipids. Increasing the amount of soy flour led to an increase in the maximum number of viable yeast cells and ethanol production. It was possible in 4 days to reach 21% (v/v) ethanol by adding 4% soy flour as source of unsaturated fatty-acyl residues to the fermentation medium. Soy flour not only increased yeast population but also enhanced the physiological properties of yeast cells to be ethanol tolerant in the anaerobic culture.

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Methionine Analogue Probes Functionally Important Residues in Active Site of Methionyl-tRNA Synthetase

  • Jo, Yeong-Joon;Lee, Sang-Won;Jo, Myung-Kyun;Lee, Jee-Woo;Kang, Mee-Kyoung;Yoon, Jeong-Hyeok;Kim, Sung-Hoon
    • BMB Reports
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    • v.32 no.6
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    • pp.547-553
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    • 1999
  • Aminoacyl-tRNA synthetases are essential enzymes catalyzing the attachment of specific amino acids to cognate tRNAs. In the present work, the substrate analogue L-methionine hydroxamate was used to identify functional residues located in the active site of the E. coli methionyl-tRNA synthetase (MetRS). This compound inhibited bacteria, yeast, and human MetRS activities to a similar degree, suggesting a conserved active site structure and mechanism between MetRSs of different phylogenetic domains. Mutants of the E. coli MetRS resistant to methionine hydroxamate were also isolated. These mutants contained a substitution either at T10, Y15, or Y94. These residues are highly conserved among the different MetRSs and the mutants showed decreased aminoacylation activity, suggesting their functional and structural significances. The putative roles of these residues are discussed on a structural basis.

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Effect of Filler Types on Phenol-Formaldehyde Resin Adhesive for Plywood (충전제의 종류가 합판용 페놀수지 접착제에 미치는 효과)

  • Oh, Yong-Sung
    • Journal of the Korean Wood Science and Technology
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    • v.26 no.3
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    • pp.48-52
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    • 1998
  • Residues such as walnut, pinenut and peanut shells were used as a filler in adhesive for bonding radiata pine plywood. The nutshell residues were prepared by simply drying to 8% moisture content and grinding the dry material using a laboratory Wiley mill with a $75{\mu}m$ (200 mesh) screen. The nutshells residues were compared to a commercial filler commonly used in adhesives by the structural plywood and laminated veneer lumber industry in the United States. The adhesive mixes were made by following the recommended procedure of Georgia-Pacific Resins, Inc., using phenol-formaldehyde resin. For each filler type, three-ply plywoods, 6 mm nominal thickness and 30 by 30 cm in size, were fabricated at two press times (4 and 5 min) and around 30 minute assembly time. Evaluations of the nutshell residues were carried out by tension shear tests after cyclic boil tests on plywood. The results of the performance test included tension shear strength and wood failure. All plywoods made with the nutshell fillers were comparable to those made with the control filler. These results indicate that nutshell residues would be suitable as filler for plywood adhesives.

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