• Title, Summary, Keyword: acidic herbicides

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Inter-lab validation for the derivatization method by TFE/TFAA of acidic herbicides (산성 제초제류의 TFE/TFAA 유도체화 방법에 대한 실험실간 정도관리)

  • Pyo, Hee-Soo;Park, Song-Ja;Lee, Kang-Jin;Hong, Jong-Ki;Shin, Ho-Sang
    • The Korean Journal of Pesticide Science
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    • v.9 no.2
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    • pp.159-165
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    • 2005
  • A sensitive derivatization method by using the TFE/TFAA as derivative reagent is proposed for the determination of acidic herbicides in water, by using this method, method detection limits are improved by 10 times and sample volumes are decreased by 5 times compared with other methods such as U.S. EPA and SPEED 98. And also, in order to suggest higher creditable standard operating procedure (SOP), intra- and inter-lab validation test carried out by four laboratories include our lab. The results of intra and inter-lab validations in same experimental conditions show good linearity in given range of concentrations as a $0.1{\sim}10.0$ ng/ml, and range of accuracies and precisions show $-20.5{\sim}12.2$ bias%, $0.55{\sim}24.48%$ (for intra-lab validation) and $-6.66{\sim}0.80 bias%$, $1.92{\sim}13.86%$ (for inter-lab validation), respectively.

Chemical Stabilization Study for Sulfonylurea Herbicides (Sulfonylurea계(系) 제초제(除草劑)의 화학적(化學的) 안정성(安定性))

  • Chen, Chia-Chung
    • Korean Journal of Weed Science
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    • v.17 no.2
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    • pp.135-138
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    • 1997
  • Sulfonylureas are highly active herbicides which can be applied at very low rate(10-50g/ha) to control broadleaf weeds. The nature of this category of compound is, however, very unstable toward hydrolysis. Therefore, the preparation of these compounds as liquid formulation was not possible. Most of the current formulations of sulfonylurea are in dry forms such as water dispersible granule or wettable powder. Even in these dry forms, the active ingredients also encounter significant chemical decomposition. This study involves the preparation of the sulfonylurea salts by reacting the parent compound with base such as sodium hydroxide. The salt becomes stable toward hydrolysis and it turns soluble when diluted with water. This discovery makes the preparation for liquid formulation or soluble granule of sulfonylurea possible. The stoichiometry of base added to the neutral sulfonylurea is controlled quite precisely. The base has to be added enough to quench the acidic impurities in the technical material and to convert the active ingredient into salt. However, the base should not be overused to cause further saponification of the sulfonylurea salts. The chemical nature of these compounds is presented and the chemical reaction is described. New soluble liquid formulation and solid granule formulation of sulfonylurea are suggested.

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The Corrosive Laryngeal Injury of Glyphosate Surfactant Herbicide Intoxication : A Case Report and Review (글리포세이트 음독 후 발생한 후두 부식손상 1예)

  • Joo, Yeon-Hee;Kim, Jin-Pyeong;Park, Jung-Je;Woo, Seung-Hoon
    • Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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    • v.22 no.2
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    • pp.156-158
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    • 2011
  • Organophosphates are used as herbicides. Glyphosate is one of the acidic organophosphate solution of pH4.8-6. We experienced a case of laryngeal injury after glyphosate caustic ingestion. He had a mild respiratory distress, and a laryngeal granuloma was observed in endoscopy. He received treatment with oral steroid and PPI for two weeks, the laryngeal granuloma and respiratory distress were nearly disappeared. Therefore, we expect this case report to be helpful the therapeutic formulations in the damage of larynx due to glyphosate.

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Determination of 2, 4-D and 2, 4, 5-T in River Water and Drinking Water by Gas Chromatograph/Mass Spectrometer (GC/MS를 이용한 수질시료 중 2, 4-D와 2, 4, 5-T의 분석에 관한 연구)

  • 표희수;신혜승;박송자
    • Environmental health and toxicology
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    • v.15 no.3
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    • pp.107-113
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    • 2000
  • Chlorophenoxy acids are one of the most useful classes of chlorinated herbicides. Specially 2, 4-D and 2, 4, 5-T were known to endocrine distruptors. In this study, these pesticides in water samples were extracted by liquid-liquid extration at acidic conditions and then derivatization of acidic group was carried out various esterifications using by CH$_3$I/Acetone -K$_2$CO$_3$, H$_2$SO$_4$/MeOH or TFAA/TFE. That result, Sensitivities of TFE derivatized 2, 4-D and 2, 4, 5-T are prior to the others. The recoveries of 2, 4-D and 2, 4, 5-T were 98% and 82% respectively using diethyl ether as an extracting solvent.

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Studies on the Development of Liquid Chromatographic Methods for Pesticide Residues (II) : The Development of the Analytical Method for Thiocarbamates Herbicides (잔류농약의 액체 크로마토그래피 분석법 개발에 관한 연구 (II) Thiocarbamates 제초제의 잔류농약 분석법 개발)

  • Lee Dai Woon;Choi Yong Wook
    • Journal of the Korean Chemical Society
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    • v.36 no.1
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    • pp.66-74
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    • 1992
  • A method for the multiresidual simultaneous analysis of 11 thiocarbamates was studied using HPLC. Thiocarbamate in Chinese cabbage was analyzed in the order of extraction, partition, and cleanup in their optimum condition. Acetone was chosen as an extracting solvent. As a partitioning solvent, the mixture of 50% methylene chloride and petroleum ether containing extremely small water content showed good recoveries of thiocarbamate from the water layer. Partition efficiency was affected by pH of the water layer; it remained almost constant under the acidic and neutral condition while decreasing under the basic condition. The comparison done in cleanup step showed that the column chromatographic method is superior to the treatment of coagulating reagent. As an absorbent, the mixture of charcoal, magnesia, and celite with the ratio of 1 : 2 : 4 gave better recoveries and also effectively removed chlorophyll. Over the total procedure, the average recoveries for thiocarbamates in Chinese cabbage were 91% at about 2 ppm fortification level within the relative standard deviation of 8%, and the minimum detection limit (MDL) was 2.2${\sim}$9.3 ng.

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Multi-residue Pesticide Analysis in Cereal using Modified QuEChERS Samloe Preparation Method (곡물류 중 잔류농약 다성분 분석을 위한 개선된 QuEChERS 시료 정제법의 개발)

  • Yang, In-Cheol;Hong, Su-Myeong;Kwon, Hye-Young;Kim, Taek-Kyum;Kim, Doo-Ho
    • The Korean Journal of Pesticide Science
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    • v.17 no.4
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    • pp.314-334
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    • 2013
  • This study explored an efficient modified Quick, Easy, Cheap, Effective, Rugged and safe (QuEChERS) method combined with liquid chromatography-electrospray ionization with tandem mass spectrometric detection for the analysis of residues of 76 pesticides in brown rice, barley and corn including acidic sulfonylurea herbicides. Formic acid (1%) acid in acetonitrile and dispersive solid phase extractions used for extraction of pesticides and clean-up of the extract respectively. Two fortified spikes at 50 and 200 ng $g^{-1}$ levels were performed for recovery test. Mean recoveries of majority of pesticides at two spike levels ranged from 73.2 to 132.2, 80.9 to 136.8, 66.6 to 143.5 for brown rice, barley and corn respectively with standard error (CV) less than 10%. Good linearity of calibration curves were achieved with $R^2$ > 0.9907 within the observed concentration ranged. The modified method also provided satisfactory results for sulfonylurea herbicides. The method was applied to the determination of residues of target pesticides in real samples. A total of 26 pesticides in 36 out of 98 tasted samples were observed. The highest concentration was observed for tricyclazole at 1.17 mg $kg^{-1}$ in brown rice. This pesticide in two brown rice samples exceeded their MRLs regulated for rice in republic of Korea. Except tricyclazole none of the observed pesticides' concentration was higher than their MRLs. The results reveal that the method is effectively applicable to routine analysis of residues of target pesticides in brown rice, barley and corn.