气相色谱脉冲火焰光度法快速测定茶叶中12种有机磷农药残留

本文建立了超声提取,固相萃取小柱净化,GC-PFPD快速测定茶叶中12种有机磷农药残留的分析方法,重点考察并优化了茶叶中有机磷农药的提取与净化。样品经丙酮提取,PSA/活性炭固相萃取柱净化,以乙腈/甲苯混合溶液洗脱。实验结果表明各组分在0.05μg/mL～1.0μg/mL浓度范围均具有良好的线性关系,相关系数r均大于0.99,样品回收率在92.5%～109.5%之间,相对标准偏差小于11.0%,12种有机磷农药的检出限在0.005mg/kg～0.01mg/kg。     

QuEchERS法测定蔬菜中有机磷类农药多残留分析

本文运用农药多残留分析中的一种简便、快速、价格低廉的分析方法—QuEchERS法。其采用一种新的样品前处理方法,从蔬菜中提取净化残留农药(包括11种有机磷农药),运用GC/MS进行分析检测,根据有机磷农药种类差异,其最小检出限在5.6~18.2μg/kg之间,回收率在67.7%~105.3%之间,相对标准偏差不大于10.6%,实验表明本方法适用蔬菜中有机磷农药多残留分析。     

有机磷农药的残留、毒性和展望

有机磷农药问世到现在已70年了。由于它的高效、快速和广谱等特点,在农药领域一直占有重要位置,对全球农业的发展起了很重要的作用。但随着它的不断使用,也暴露出了很多问题,如高残留、毒性强等,引起了人们的高度重视。文章主要对有机磷农药的残留检测、毒性作了初步的分析,指出尽快开发替代产品是今后使用有机磷农药的方向。     

气相色谱法测定蔬菜中13种有机磷的农药残留

有机磷农药常被用于蔬菜、果树、粮食等的害虫防治,但随着农药的大量使用,在得到效益的同时,大气、水体、土壤等环境也遭到了不同程度的污染,在食品安全越来越重要的今天,蔬菜水果中的农药残留问题也已发展成为社会问题,建立蔬菜水果中农药残留量分析检测方法已成当务之急。本文采用气相色谱法对我省蔬菜中13种有机磷农药残留量进行快速测定。该方法简便、灵敏、准确,能满足有机磷农药残留量测定的要求。     

蔬菜中有机磷农药多残留的光谱特征研究

本文采用近红外光谱技术对蔬菜中有机磷农药残留的检测方法进行了研究。通过气相色谱法筛选蔬菜中有机磷农药残留后,借助近外红光谱扫描阳性样品,并对样品的原始光谱图进行预处理,构建样品近外红光谱校正模型,计算有机磷农药含量。将近红外光谱校正模型计算结果与气相色谱法测定结果相比较,结果二者间差值可接受。结论是近外红光谱校正模型操作简单,对样品处理的要求低,适用于蔬菜中有机磷农药残留分析。     

果蔬食品中有机磷农药残留量测定的不确定度评估

本文依据GB／T5009．20-2003《植物性食品中有机磷农药多种残留的测定》方法，分析了果蔬食品中有机磷农药残留量测定的不确定来源，以及各不确定度分量的计算、合成和扩展的评估方法，并列举了计算实例。     

高效液相色谱法对饮用水中农药残留的检测分析研究

在我国的农药市场中,杀虫剂品种较多,有机磷类农药就达到了30种以上,占总量的40%左右。作为一种高效、用途广的农药制品,有机磷农药被广泛用于农业防害。随着有机磷农药产量、使用量的不断增加,对水环境的污染越来越大,此类农药残留富集作用极强,若经各种渠道进入人体,将出现慢性中毒现象,甚至会对人类食品安全造成严重威胁。为此,该文采取高效液相色谱法对饮用水中农药残留进行了检测分析,以期提高检测精度,保证饮用水质量。     

浅谈农药残留快速检测仪的校准

在果蔬生产中,随着农药的大量和不合理使用,农药残留检测技术已经受到越来越多的关注和重视,成为全社会的焦点,农药残留快速检测仪得到了广泛应用。农药残留快速检测仪是基于酶抑制率法原理,用于有机磷和氨基甲酸酯类农药残留快速检测的仪器。农药残留快速检测仪是利用分光光度法测定酶催化水解与显色剂反应生成的黄色物质在仪器工作波长范围内检测的吸光度随时间的变化值,计算出抑制率,通过抑制率来判断农药残留情况。本文简单叙述了非连续波长型农药残留快速检测仪的校准方法。     

非酶纳米电化学传感器用于有机磷农药残留物 检测综述

近年来,非酶纳米电化学传感器检测有机磷农药的研究受到广泛关注。非酶纳米电化学传感器具有检测成本低、操作方便、灵敏度高、响应快速等优点。碳纳米材料、纳米金属颗粒、纳米金属氧化物和纳米导电聚合物及其复合材料的出现,大大提高了有机磷农药电化学传感器的性能。随着纳米技术的出现,在合成纳米材料用于分析物特异性检测方面取得了进展,这些材料可用于构建高特异性、强选择性和经济有效的电化学传感器,以取代其他分析技术。鉴于各类纳米材料新结构的重要性,对非酶纳米电化学传感器领域的最新研究进展进行综述,并重点介绍纳米复合材料在有机磷农药检测中的应用。     

固相萃取-双柱气相色谱法测定水中多种有机磷农药残留

针对单一气相色谱柱定性分析易出现假阳性误判的情况,采用固相萃取-气相色谱双柱技术测定环境水体中多种有机磷农药的残留量。水样中的有机磷农药通过HLB固相萃取小柱富集,经洗脱浓缩后,用DB-35MS和HP-5毛细管气相色谱柱、火焰光度检测器测定。方法的平均加标回收率为86.1%～118%,相对标准偏差为3.2%～6.8%,最低检出限为20～40ng/L,可满足环境水体中痕量有机磷农药残留的分析需要。     

Visible light photocatalytic degradation of paraoxon and parathion pesticides on carbon-doped TiO<Subscript>2</Subscript> nanorod thin films

In the present work the nanostructured carbon-doped TiO₂ thin films with nanorod morphology were deposited on glass substrate by a combination of ultrasonic and chemical vapor deposition methods, and for the first time were applied for the photocatalytic degradation of paraoxon and parathion organophosphorus pesticides under visible light irradiation. X-ray Diffraction, X-ray photoelectron spectroscopy, diffuse reflectance spectroscopy, and scanning electron microscopy techniques were used for characterization of the prepared thin films. Obtained results show that presence of carbon element and also special nanorod morphology of the thin films remarkably improve the optical properties of TiO₂ in visible light region and results in the good visible light photocatalytic activity of the thin films for degradation of the pesticides. The photonic efficiencies of the prepared thin films were also examined based on the international ISO-10678:2010 standard protocol for photocatalytic degradation of methylene blue under UV light irradiation. The results show a maximum photonic efficiency of 0.0312% for the carbon-doped TiO₂ thin film with 570 nm thickness, which compared to a reference standard TiO₂ films indicates a 30% improvement in photonic efficiency.     

Chlorination of organophosphorus pesticides in natural waters

Unknown second-order rate constants for the reactions of three organophosphorus pesticides (chlorpyrifos, chlorfenvinfos and diazinon) with chlorine were determined in the present study, and the influence of pH and temperature was established. It was found that an increase in the pH provides a negative effect on the pesticides degradation rates. Apparent second-order rate constants at 20 degrees C and pH 7 were determined to be 110.9, 0.004 and 191.6 M(-1) s(-1) for chlorpyrifos, chlorfenvinfos and diazinon, respectively. A higher reactivity of chlorine with the phosphorothioate group (chlorpyrifos and diazinon) than with the phosphate moiety (chlorfenvinfos) could explain these results. Intrinsic rate constant for the elementary reactions of chlorine species with chlorpyrifos and diazinon were also calculated, leading to the conclusion that the reaction between hypochlorous acid and the pesticide is predominant at neutral pH. The elimination of these pesticides in surface waters was also investigated. A chlorine dose of 2.5 mg L(-1) was enough to oxidize chlorpyrifos and diazinon almost completely, with a formation of trihalomethanes below the EU standard for drinking water. However, the removal of chlorfenvinfos was not appreciable. Therefore, chlorination is a feasible option for the removal of organophosphorus pesticides with phosphorothioate group during oxidation and disinfection processes, but not for the elimination of pesticides with phosphate moiety.     

全自动在线HS-SPME-GC-MS/MS检测鱼塘投毒案件水样中的13种有机磷农药

建立全自动在线顶空固相微萃取-气相色谱串联质谱技术(HS-SPME-GC-MS/MS)检测鱼塘投毒案件水样中13种有机磷农药的方法。将2 mL水样中加入0.6 g氯化钠(NaCl)置于20 mL顶空瓶中,使用直径为100μm的聚二甲基硅氧烷(PDMS)萃取纤维,在75℃条件下萃取45 min,采用GC-MS/MS多反应监测模式(MRM)进行检测。13种有机磷农药在线性范围内线性关系良好,标准曲线相关系数(r²)>0.99,方法检出限为0.002-0.5 ng/mL,定量限为0.006-1.8 ng/mL,精密度在1.92%-17.10%之间。该方法灵敏度高,并且操作简单,样品的处理与分析过程全自动进行,可提高工作效率,适用于鱼塘投毒案件水样中13种有机磷农药的检测。     

Adsorption and removal of organophosphorus pesticides from environmental water and soil samples by using magnetic multi-walled carbon nanotubes @ organic framework ZIF-8

In this study, the functional adsorbent metal–organic framework ZIF-8/magnetic multi-walled carbon nanotubes (M-M-ZIF-8) was successfully prepared for removal of eight organophosphorus pesticides from environmental water and soil samples. The M-M-ZIF-8 was characterized and their adsorption capacity was evaluated based on their isothermal adsorption curves. The results suggest that ZIF-8 particles are deposited on the surface of the magnetic MWCNTs via coordination–polymerization strategy. In addition, M-M-ZIF-8 has high static adsorption capacities for organophosphorus pesticides because of its high specific surface area and porous structure. The static adsorption data fit the Freundlich adsorption model better than the Langmuir model. Under the optimized conditions, M-M-ZIF-8 was successfully applied to remove the eight organophosphorus pesticides from environmental water and soil samples. A possible mechanism is valence-electron-driven adsorption by sharing or exchanging of electrons between the organophosphorus pesticide molecules and the vacant active sites of M-M-ZIF-8. Therefore, M-M-ZIF-8 is a promising hybrid adsorbent for adsorption and removal of organic pollutions from the environment.     

Trace level determination of organophosphorus pesticides in water with the new direct-electron ionization LC/MS interface

A new LC/MS method for the determination of organophosphorus pesticides in water, based on the use of direct-electron ionization (EI) interface, is presented. Direct-EI is a new device that, in a very simple fashion, couples a nano-HPLC system with a mass spectrometer equipped with electron ionization capability. The nanoscale liquid flow allows for a direct introduction of eluate into the ion source and, after nebulization, for its ionization under typical EI conditions. Library-matchable EI spectra are generated for a choice of full scan or SIM detection of the analytes. In our case, a selection of organophosphorus pesticides, commonly distributed in local sugar beet cultivation, were considered. The new interface permits a very sensitive detection of the analytes in a wide range of linear response (0.09-9 ng). When applied to a real sample, the method allowed detecting four different pesticides at a concentration level of approximately 3 ng x L(-1).     

Potentiometric sensing of chemical warfare agents: surface imprinted polymer integrated with an indium tin oxide electrode

Rapid and specific recognition of methylphosphonic acid (MPA), the degradation product of nerve agents sarin, soman, VX, etc., was achieved with potentiometric measurements using a chemical sensor fabricated by a surface imprinting technique coupled with a nanoscale transducer, indium tin oxide (ITO). An octadecylsiloxane thin layer was covalently bound to the ITO-coated glass surface in the presence of MPA. After extraction of MPA, potentiometric measurements showed selective detection of MPA. The selectivity of the sensor has been tested on other alkylphosphonic acids, such as ethylphosphonic acid and propylphosphonic acid, as well as tert-butylphosphonic acid. The viability of the sensor in the presence of other chemical analogues, such as organophosphorus pesticides and herbicides, was investigated.     

Prediction of substructure and toxicity of pesticides with temperature constrained-cascade correlation network from low-resolution mass spectra.

Artificial neural networks are trained to predict the toxicity or active substructures of organophosphorus pesticides and then are applied to screening GC/MS data for environmentally hazardous compounds. Every mass spectral scan in the chromatographic run is classified, and separate chromatograms are obtained for either toxicity or substructure classes. Classification of mass spectra allows the detection of chromatographic peaks from potentially hazardous compounds that may be missing from the reference database. The neural network models predict substructures and toxicity from mass spectra without first determining the complete configurational structure of the pesticides. Temperature constrained-cascade correlation networks (TCCCN) were used because they are self-configuring networks that train rapidly and robustly. The toxicity classes are defined by the World Health Organization, and the substructure classes are standard organophosphorus pesticide groupings. The TCCCN models are used to mathematically resolve peaks in the chromatograms by substructure and toxicity. Evaluations yielded classification rates of 97 and 84% for substructure and toxicity, respectively.     

蜂蜜中8种有机磷农药残留量的气相色谱法测定

本文建立了气相色谱法测定蜂蜜中8种有机磷农药(敌敌畏、久效磷、乐果、甲基嘧啶磷、毒死蜱、杀螟硫磷、对硫磷、喹硫磷)残留量的检测方法。蜂蜜样品用乙酸乙酯提取后气相色谱-火焰光度检测器(GC-FPD)测定。8种有机磷农药在(10.0~100.0)g/L范围内,质量浓度与峰面积呈良好的线性关系(r>0.9993);3个不同加标水平的方法回收率为85%~110%。本方法准确、重现性、精密度好,已成功地应用于福建当地主要蜂蜜中有机磷农药残留的测定。     

流动注射——荧光法测定水样中敌敌畏含量

有机磷农药敌敌畏(DDVP)在过硼酸钠的作用下可将胺类化合物氧化成可发荧光的产物。本研究根据这一原理,建立了定量测定这类农药的流动注射——荧光分光光度法。该方法具有分析速度快、操作方便、重现性好、灵敏度较高等特点。