麦麸酯酶对有机磷及氨基甲酸酯类农药的动力学特性

为探讨有机磷及氨基甲酸酯类农药对麦麸酯酶的抑制作用,以酶活抑制率为指标,通过测定酶动力学常数(Ki、Ka、K2)及半数抑制浓度(IC50)揭示麦麸酯酶的动力学特性。结果显示:麦麸酯酶对3种有机磷农药的敏感性大小顺序依次为:敌敌畏甲基对硫磷乐果,其对麦麸酯酶的IC50分别为0.176、1.754、2.583 mg/L;对3种氨基甲酸酯类农药的敏感性大小依次为:叶蝉散西维因丁硫克百威,其对麦麸酯酶的IC50分别为0.489、0.799、2.035 mg/L;各农药抑制麦麸酯酶的动力学常数(Ki、Ka、K2)及IC50值表明,不同农药对麦麸酯酶的抑制作用存在不同程度的选择性,农药与麦麸酯酶的亲和力强弱是导致麦麸酯酶对农药敏感性差异的主要原因;运用该方法检测蔬菜和水果中农药残留,得出莴笋叶、四季豆和葡萄中含有农药,且确定葡萄中为乐果残留。该研究可为麦麸酯酶应用于农药检测提供一定的理论基础。     

高分子多孔微球富集—HPLC法测定水体中的有机磷

本文提出应用国产高分子多孔微球－ＧＤＸ系列富集－反相高效液相色谱法测定废水中久效磷、乐果、甲基对硫磷三种有机磷农药分析方法。三种不同型号色谱固定相（ＧＤＸ－１０２，ＧＤＸ－３０１和ＧＤＸ－５０１）对水体中ｎｇ／ｍＬ级久效磷、乐果和甲基以硫磷的富集效率分别达到８５％、８２％和９３％以上，采用μ－Ｂｏｎｄａｐａｋ Ｃ１８作固定相，以６０％甲醇水溶液作流动相，对三种有机磷农药的分离度可达到１．２以上。本     

水样中痕量有机磷农药的膜萃取-气相色谱法测定

制作了涂渍植物来源的酶和不同化合物的萃取膜，萃取富集了水样中的有机磷农药和农药中间体残留。实验表明：涂有不同物质的萃取膜对不同农药有选择性地富集。利用戊二醛膜对河流水样中的硫代磷酸三甲酯和精胺进行富集，用气相色谱－火焰光度检测器检测，回收率在68％－103％之间；检测限为0.1μg/L。方法可满足水体中痕量有机磷农药残留检测的要求。     

植物酯酶法检测有机磷农药残留量研究

对植物酯酶作为抑制剂检测有机磷农药的体系进行了研究，采用均匀设计法优化了检测条件；对可能影响酶活的干扰因素进行了分析；比较了7种有机磷农药对酶的抑制作用；建立了利用植物酯酶检测有机磷农药的方法，并应用于蔬菜样品中有机磷残留量检测。     

用于农药残留快速检测的两种酶的比较

以商品乙酰胆碱酯酶(C3389,Ⅵ-S,从电鳗中提取)和自制鸡肝酶为农药检测用酶,比较了不同浓度的敌敌畏、敌百虫、马拉硫磷和西维因对这两种酶的乙酰胆碱酯酶活力和总酯酶活力的抑制情况。结果表明,鸡肝酶的乙酰胆碱酯酶活力较低,而其总酯酶活力对4种农药的灵敏度与商品乙酰胆碱酯酶活力的灵敏度相近,且总酯酶活力对除马拉硫磷外的其余3种农药的检出限都较乙酰胆碱酯酶低。同时对总酯酶活力测定的pH进行了优化,发现pH6．5(40mmol／L柠檬酸盐缓冲液)时总酯酶活力较高。     

工业乐果的薄层层析—溴化法分析研究

乐果是一种高效低毒的有机磷杀虫剂,它是我国农药品种中吨位较大、用途较广的一种杀虫剂。随着我国社会主义革和建设事业的飞速发展,乐果的生产技术不断革新,有了很大改进,但到目前为止还没有一个较为满意的快速、准确的分析方法。目前,测定乐果有效成分0,0-二甲基-S-(N-甲胺甲酰基)二硫代磷酸酯常用     

植物酯酶应用于有机磷农药残留分析技术的研究进展

有机磷农药残留在食品中,进入人体危害人类健康.因此,快速而灵敏的检测技术是预防农药残留危害的前提条件.而酶抑制技术正是一项快速检验技术.本文作者介绍了农药残留分析的现状,详细分析了植物酯酶应用于农药残留分析技术的研究进展.     

交联型"纳米花"酶用于拟除虫菊酯农药的高效水解研究

该文制备了交联型猪肝酯酶杂化“纳米花”酶（CL－PLE－NFs）,并对其制备条件进行了优化。在最佳条件下,CL－PLE－NFs的酶活为游离酶的231%,最大反应速率（Vmax）是游离酶的134%。同时,将交联型纳米花酶在4 ℃下贮藏320 d后,仍能保留70.85%的活力,表现出良好的贮藏稳定性。此外,将CL－PLE－NFs应用于拟除虫菊酯类农药的水解实验,发现其对Ⅰ型和Ⅱ型的拟除虫菊酯类农药均有较优的水解能力,在5 min内对11种拟除虫菊酯农药的水解率均在55%以上。同时,循环使用12次后,CL－PLE－NFs对溴氰菊酯农药的水解效率仍然可达65.37%。     

高分子多孔微球富集－HPLC法测定水体中的有机磷

本文提出应用国产高分子多孔微球－ＧＤＸ系列富集－反相高效液相色谱法测定废水中久效磷、乐果、甲基对硫磷三种有机磷农药分析方法。三种不同型号色谱固定相（ＧＤＸ－１０２，ＧＤＸ－３０１和ＧＤＸ－５０１）对水体中ｎｇ／ｍＬ级久效磷、乐果和甲基对硫磷的富集效率分别达到８５％、８２％和９３％以上。采用μ－ＢｏｎｄａｐａｋＣ１８作固定相，以６０％甲醇水溶液作流动相，对三种有机磷农药的分离度可达到１．２以上。本法用于分析水体中有机磷农药，结果令人满意。     

制备分离农药甲霜灵对映体的高效液相色谱法

用高效液相色谱法对自制的纤维素－三（3，5－二甲基苯基氨基甲酸酯）手性制备柱的手性拆分能力进行了评价，并且在此制备柱上完成了对手性农药甲霜灵进行了半制备分离；同时对手性农药甲霜灵在纤维素－三（苯基氨基甲酸酯）、直链淀粉－三（苯基氨基甲酸酯）、纤维素－三（4－甲基苯甲酸酯）手性分析柱上的手性拆分进行了研究。     

Rapid multiresidue screening method for organophosphate pesticides in vegetables

Summary A rapid and efficient multiresidue extraction procedure using ethyl acetate and sodium sulfate has been applied to the analysis of diazinon, methamidophos, chlorpyrifos, malathion, parathion, parathion-methyl, dimethoate and monocrotophos residues in many different kinds of vegetables. No cleanup step was required Concentrated extracts were analysed by gas chromatography with flame photometric detection in phosphorus mode. Recovery studies were performed in six kinds of matrices at two fortification levels. Recoveries were in the range 80–115%. The limit of quantification of the analytical method has been estimated as 0.01 ppm for diazinon, methamidophos and malathion, 0.03 ppm for chlorpyrifos, parathion, parathion-methyl and dimethoate and 0.1 ppm for monocrotophos. Experiments showed that potentially it should be possible to develop a rapid and universally applicable method for organophosphate pesticide residues in different matrices.     

基质效应对有机磷农药测定的影响及其解决方法

该文以液液萃取-气相色谱法探讨了基质对乐果、甲基对硫磷、马拉硫磷和对硫磷4种有机磷测定的影响以及解决方法.研究表明,气相色谱法测定有机磷农药的过程中基质效应显著存在,其基质增强比例为1.01 ～3.46.基质效应由基质种类及含量、有机磷农药种类及浓度等因素决定,同时与萃取溶剂、测定条件(如衬管、进样口温度等)有关.不同萃取溶剂对有机磷农药的萃取效率不同,但均存在基质增强效应;当进样口温度为260 ℃时,可最大程度降低基质在衬管中的残留,且不造成有机磷农药的分解;衬管则应首选带玻璃棉的.实际样品/标准样品的交替进样方式可以降低基质效应强度,但难以达到回收率要求,而校正因子校正法及分析保护剂法则是降低或消除基质效应的可行办法.     

气相色谱-火焰光度法测定土壤中有机磷农药残留

建立了气相色谱-火焰光度(GC-FPD)分析土壤中敌敌畏、氧化乐果、二嗪农、乐果、甲基对硫磷、马拉硫磷、对硫磷、水胺硫磷、喹硫磷等9种有机磷农药残留量的方法。样品用丙酮-二氯甲烷(1:3)提取,浓缩、定容后用Hp-5MS(30m×0.25 mm×0.25μm)毛细管柱分离,FPD检测器检测。方法回收率在68.71%～110.39%之间;RSD在5.5%～11%之间;检出限在0.397～1.60μg/mL之间,方法可用于环境土壤样品中有机磷农药残留的测定。     

Research progress on pesticide residue detection based on microfluidic technology

The problem of pesticide residue contamination has attracted widespread attention and poses a risk to human health. The current traditional pesticide residue detection methods have difficulty meeting rapid and diverse field screening requirements. Microfluidic technology integrates functions from sample preparation to detection, showing great potential for quick and accurate high-throughput detection of pesticide residues. This paper reviews the latest research progress on microfluidic technology for pesticide residue detection. First, the commonly used microfluidic materials are summarized, including silicon, glass, paper, polydimethylsiloxane, and polymethyl methacrylate. We evaluated their advantages and disadvantages in pesticide residue detection applications. Second, the current pesticide residue detection technology based on microfluidics and its application to real samples are summarized. Finally, we discuss this technology's present challenges and future research directions. This study is expected to provide a reference for the future development of microfluidic technology for pesticide residue detection.     

A fluorescent dipyrrinone oxime for the detection of pesticides and other organophosphates

An N,N-carbonyl-bridged dipyrrinone oxime has been synthesized and studied as a potential sensor for organophosphates. The molecular sensor underwent a drastic colorimetric response upon formation of the adduct. The pesticide dimethoate was found to produce the biggest spectral response, with a limit of detection equal to 4.0 ppm using UV-visible spectroscopy. Minimal fluorescence "turn on" via a PET mechanism was seen, and molecular modeling studies were used to explain the lower than expected PET response. The X-ray crystal structure of the fluorescent dipyrrinone oxime was also obtained.     

Multi-Residue Analysis of Some Polar Pesticides in Water Samples with SPE and LC–MS–MS

In the present study a multi-residue analytical method was developed for monitoring some polar pesticides such as acephate, methamidophos, carbofuran, isoproturon, dimethoate in water with SPE (solid-phase extraction) and LC–MS–MS. Acetochlor was taken as surrogate, and alachlor as internal standard. SPE with different types of columns was compared with LLE (liquid-liquid extraction). Further, the breakthrough volume for different pesticides was determined. The results showed that the selected pesticides can be determined very sensitively with LC–MS–MS. The minimum detectable quantity (MDQ) for each pesticide was about 1.0 ng. To date, SPE cartridge studies showed that the Oasis HLB cartridges were suitable for further studies. However, for Oasis HLB cartridge, different pesticide showed different breakthrough volume. The results showed that for acephate and methamidophos, the breakthrough volume was about 30 mL of water sample, much less than the breakthrough volume of other pesticides studied. Because of the higher vapor pressure and higher Henry's constant of methamidophos, dimethoate and carbofuran, much attention should be paid on their losses in the evaporation step of the experiment. This analytical method can be applied to determine pesticide contamination in environmental water samples. Revised: 12 September 2005 and 21 October 2005     

Oligonucleotides and pesticide regulated peroxidase catalytic activity of hemin for colorimetric detection of isocarbophos in vegetables by naked eyes

A novel colorimetric sensing platform based on the peroxidase activity of hemin regulated by oligonucleotide and pesticide was reported for the ultrasensitive and selective detection of isocarbophos. Oligonucleotides can accumulate on the surface of hemin in acid condition and temporarily inhibit its catalytic activity, which results in the loss of one electron of TMB molecule and produce the blue products. With the addition of isocarbophos, the pesticide molecules can interact with oligonucleotides to form some complexes, which relieve the inhibition of ssDNA to hemin and further enhance its catalytic activity. Thus, the TMB molecules are further oxidized to lose another electron and produce the yellow product in a few minutes, which has the characteristic absorption peak at 450 nm. The color change of the sensing system is related to the amount of isocarbophos, so this method can quickly discriminate whether the target pesticide exceeds the maximal residue limit just by naked eyes. To improve the performance of sensing platform, some important parameters like buffer condition and ssDNA have been investigated, and the peroxidase activity of hemin was further studied to verify the catalytic mechanism. The proposed sensing platform has a detection limit as low as 0.6 μg/L and displays good selectivity against other competitive pesticides. Moreover, the developed sensing platform also exhibits favorable accuracy and stability, indicating that it has potential applications in the detection of pesticide residues in agricultural products.

A novel colorimetric sensing platform based on oligonucleotides and pesticide regulation; the peroxidase catalytic activity of hemin was firstly reported for the ultrasensitive and selective detection of isocarbophos pesticide.

     

Rapid Determination of Dimethoate with a Surface Acoustic Wave Impedance Sensor System

Abstract

Based on the principle of enzyme inhibition, a novel and sensitive lipase biosensor to determine organophosphorus pesticide is presented. Contact of the enzyme with pesticide samples results in specific inhibition of enzyme activity. Sensor calibration was possible by correlating the inhibition of enzyme activity with various concentrations of pesticide compound in a buffer solution. The sensor was successfully used to determine pesticide concentrations ranging from a low of 167ng/ml to 1.34μg/ml, and the detection limit is 81ng/ml. The effects of temperature, pH value, incubation time and solvent were also investigated. The sensor was also applied to the determination of dimethoate residues in the peel and flesh of tomato.     

人参中有机磷农残的基质固相分散-HPLC同时快速分析

建立了基质固相分散-高效液相色谱法(MSPD-HPLC)对中药材人参中的三种有机磷农药甲胺磷、甲基对硫磷和乙基对硫磷残留量进行快速分析:. 将HPLC法应用于有机磷农药残留量的检测, 分别采用中性Al2O3和体积比为8%的乙酸乙酯-正己烷作为MSPD的分散剂和洗脱剂, 对分析方法的质量控制问题进行了详细讨论, 并对不同种类的人参中药材进行了准确的定性定量分析. 该方法的线性范围为0.20～10.00 mg•L－1, 相关系数(R)大于0.99815, 相对标准偏差(RSD)均小于11.54%, 检测限(LOD)低于0.017 mg•L－1, 样品的加标回收率为87.29%～92.43%. 其线性范围、相关系数、准确度、精密度和LOD等指标均满足有机磷农残分析的要求.     

Determination of Dimethoate in Olive Oil by Adsorptive Stripping Square‐Wave Voltammetry

A method for the determination of dimethoate in olive oil by adsorptive stripping square‐wave voltammetry has been developed on the base that this pesticide is hydrolyzed in basic media giving rise to an adsorptive‐reductive peak at ?0.780 V. Extraction of dimethoate from olive oil with ethanol‐water and posterior clean‐up with C18 cartridges is carried out. Response Surface Methodology has been used for the optimization of the extraction procedure. A matrix effect is observed in olive oil extract; therefore the standard addition method must be used. The detection limit is 19.00 ng g^?1 and recoveries for three levels of fortification are ranged from 79.9% to 104.5%.