Novel method for the determination of five carbamate pesticides in water samples by dispersive liquid-liquid microextraction combined with high performance liquid chromatography

A novel method for the determination of five carbamate pesticides （metolcarb, carbofuran, carbaryl, isoprocard and diethofencard） in water samples was developed by dispersive liquid-liquid microextraction （DLLME） coupled with high performance liquid chromatography-diode array detector （HPLC-DAD）. Some experimental parameters that influence the extraction efficiency were studied and optimized to obtain the best extraction results. Under the optimum conditions for the method, the calibration curve was linear in the concentration range from 5 to 1000 ng mL^-1 for all the five carbamate pesticides, with the correlation coefficients （r^2） varying from 0.9984 to 0.9994. Good enrichment factors were achieved ranging from 80 to 177- fold, depending on the compound. The limits of detection （LODs） （S/N = 3） were ranged from 0.1 to 0.5 ng mL^-1. The method has been successfully applied to the analysis of the pesticide residues in environmental water samples.

Probit Analysis of Carbamate-Pesticide-Toxicity at Soil-Water Interface to N_2-Fixing Cyanobacterium Cylindrospermum sp.

Toxicity-data of two carbamate insecticides, carbaryl and carbofuran, and three fungicides, ziram, zineb and mancozeb with rice-field N2-fixing cyanobacterium Cylindrospermum sp., obtained by in vitro growth and at soil-water interface, were analyzed by the probit method. Growth enhancing concentration, no-observed effective concentration, minimum inhibitory concentration, the highest permissive concentration and lethal concentration100 （LCloo） were determined experimentally. The LC^o values of carbaryl, carbofuran, ziram, zineb and mancozeb in N2-fixing liquid medium were 56.2, 588.8, 0.07, 4.2 and 3.4 IJg/mL, respectively, whereas the corresponding LCloo values were 100.0, 1500.0, 0.17, 25.0 and 9.0 IJg/mL, respectively. The LC50 values of these pesticides in succession in N2-fixing agar medium were 44.7, 239.9, 0.07, 1.8 and 2.3 IJg/mL, respectively, whereas the corresponding LC100 values were 100.0, 600.0, 0.17, 10.0 and 7.0 IJg/mL, respectively. Similar results with nitrate supplemented liquid and agar media indicated that nitrate supplementation had toxicity reducing effect. The LCso and LC^oo values of toxicity in the N2-fixing liquid medium at soil-water interface were 91.2 and 200.0 IJg/mL for carbaryl, 2 317 and 6 000 pg/mL for carbofuran, 0.15 and 0.50 pg/mL for ziram, 16.4 and 50.0 pg/mL for zineb, and 7.2 and 25.0 pg/mL for mancozeb, respectively. Each LC^oo value at soil- water interface with a pesticide was significantly higher than its corresponding LCloo value at liquid/agar media. It can be concluded that, under the N2-fixing conditions, the cyanobacterium tolerated higher levels of each pesticide at soil-water interface.

Enzyme Inhibition Rate Method for Rapid Detection of Organophosphorus and Carbamate Pesticides in Cowpea

[Objectives ] The paper was to explore enzyme inhibition rate method for rapid detection of organophosphorus and carbamate pesticides in cowpea. [ Methods ] Acetylcholinesterase （ACHE） was added to cowpea extract, to determine the inhibition rate of extract against enzyme. The influences of different sampiing methods and sampling parts on detection results were compared. [ Results] The positive rate of standard sampling was 18.18% higher than that of non-stand- ard sampling, and the positive rate of samples collected from cowpea tail was 16.67% higher than that collected from other parts. [ Condmions] Enzyme inhibi- tion rate method is suitable for rapid detection of organophosphorus and carbamate pesticides in cowpea.

Simultaneous determination of 6 carbamate pesticides and relevant metabolites in oilseeds and oil with the modified fast QuEChERS method by ultra-performance liquid chromatography-tandem mass spectrometry

A sensitive and reliable method was developed and validated for the simu1taneous determination of 6 carbamate pesticides and relevant metabolites based on the modified fast QuEChERS(quick,easy,cheap,effective,rugged and safe)method combined with ultra-performance 1iquid chromatography-tandem mass spectrometry(UPLC-MS/MS).The method was also applied in the analysis of 23 commonly consumed oilseeds and oil samples.The sample was extracted with acetonitrile for three times and then the extracted solution was filtered directly though 250 mg precipitated silica adsorbent(PSA)and 250 mg Cis The mobile phase was water(containing 0.1%formic acid)and acetonitrile.The extemal standard protocols were adopted to validate the method in terms of recovery,1inearity,precision,sensitivity,and relative standard deviation(RSD)under the optimized conditions.The linear calibration curves with different ranges were established with R^(2)>0.9973,limit of detections(LODs)ranged from 0.100μg/kg to 20000μg/kg and limit of quantitations(LOQs)ranged from 0.300μg/kg to 6.000μg/kg.The LODs meets the detection requirement for the maximum residue limits in practical samples.Meanwhile,the recoveries ranged from 60.2%to 116.6%with associated RSDs ranged from 0.33%to 5.35%in 10 oilseeds matrices and ranged from 61.9%to 116.9%with RSDs ranged from 0.30%to 5.02%in 13 oil matrices.These features do make the UPLC-MSMS an ideal analytical platform for accurate and high throughput analysis of carbamates residues in the complex matrix.

混配农药中毒防治研究

首次在我国开展大规模的混配农药中毒流行病学调查,发现接触混配农药是当前发生农药中毒的重要危险因素,为针对性的预防提供了科学依据。毒理学研究证实多数农药混剂呈增毒效应或协同作用,且与其毒代动力学变化有密切关系,为今后开发高效、低毒的混配农药提供了毒理学依据。在国内外首次建立甲基对硫磷单克隆抗体酶联免疫测定法,并成功研制便携式血胆碱酯酶快速测定仪;这些检测接触、效应生物标志物的灵敏、特异、便捷的方法已试用于现场,并具有开发为产品的前景。同时还发现对氧磷酶基因在192位点的单核苷酸多态性,可能是甲基对硫磷免疫毒性作用的易感性生物标志物之一。在总结不同类别农药混配后所致中毒的临床表现特点和规律的基础上,修订现行的农药中毒诊断标准,增添了有机磷单剂及混剂中毒所致“中间期肌无力综合征”的新内容,将提高我国农药中毒的诊治水平。本研究主要成果达国内领先和国际先进水平。