基质固相分散技术在农药残留分析中的应用

基质固相分散技术是1989年提出和发展起来的一种新的样品前处理技术,它能够直接处理固态、半固态和粘稠样品,大大减少了样品处理步骤和溶剂的使用量,缩短分析时间。本文主要介绍了其原理、影响因素及在农药残留分析中的应用。     

蔬菜中有机磷和氨基甲酸酯农药残留GC-MS-SIM分析

我国对食品中农药残留的检测正在不断地探索快速准确的有效方法。现在普遍采用气相色谱法或气相色谱一质谱全扫描法检测蔬菜中农药残留,由于蔬菜中组成成份复杂,本底干扰较大,而且不同农药品种的理化性质差异较大,因此单纯用气相色谱法容易产生误判。本文介绍一种用气相色谱．质谱选择离子扫描法,同时检测蔬菜中15种有机磷和氨基甲酸酯农药残留的方法,该方法对农药残留检测具有定性准确、灵敏度高的特点。     

A validated and fast procedure for FTIR determination of Cypermethrin and Chlorpyrifos

A FTIR methodology has been developed for the simultaneous determination of Cypermethrin and Chlorpyrifos in pesticide commercially available formulations. The method involves the extraction of both active principles with CHCl₃ and direct measurement of the peak area values between 1747 and 1737 cm⁻¹ corrected with a baseline defined at 2000 cm⁻¹ for Cypermethrin and peak height values established at 1549 cm⁻¹ corrected using a baseline situated at 1650 cm⁻¹ for Chlorpyrifos.The limits of detection achieved were of the order of 0.7 and 0.4% (w/w), and the relative standard deviation 0.4 and 0.2% for Cypermethrin and Chlorpyrifos, respectively. The developed procedure provided statistically comparable results with those obtained by HPLC, for a series of commercial samples, which validated the FTIR method. The procedure developed reduces organic solvent consumption, per sample preparation, from 51 ml CH₃CN required for HPLC to 2.5 ml CHCl₃, and reduces waste generation also increasing the sample measurement frequency, from 3 to 30 samples/h, as compared with the HPLC-UV reference method.     

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。     

高效液相色谱法测定水体系中N—（2,4—二甲苯基）—N‘—甲基甲脒盐酸盐

本文研究了用高效液相色谱法测定水体中单甲脒盐酸盐的分析方法，峰高定量，标准曲线的线性范围为０－１０００ｍｇ／Ｌ，回收率在８７％－９８％之间，直接进样分析检测限为０．３５ｍｇ／Ｌ。此方法已应用于细胞反应中单甲脒盐酸盐的测定。     

Improved detection of toxic chemicals using bioluminescent bacteria

A sensitive, rapid and simple bioluminescent (BL) assay using bioluminescent bacteria to detect the toxic activity of several chemicals is described. This assay is based on the measurement of inhibition of light production of a bioluminescent bacterial strain, isolated from seawater, in the presence of different toxins like heavy metals, organic chemicals, such as benzene, toluene, ethylbenzene, xylene (BTEX) and a wide range of pesticides in environmental samples. The improvement with respect to other commercial and non-commercial bioluminescent assays consists of the possibility to work at room temperature without the need to thermostat, thus allowing the use of simpler and low cost instruments, or to improve the assay using a microplate format, which makes it possible to analyse several samples also continuously for several hours. Using lyophilised bacteria, the assay is performed in less than an hour, without any bacterial cultivation, which makes the test suitable for rapid and sensitive evaluation of chemical pollutants in environmental samples.     

Comparison of pesticides levels in grape skin and in the whole grape by a new liquid chromatographic multiresidue methodology

The increasing interest in the study of pesticides in grapes is justified from an enological point of view, since some pesticides can interfere with fermentative microflora used in wine production, as well as, with the consumer’ safety. Considering that washing grapes before consumption is the standard procedure, the study of the effect of washing on the residue concentration is required to assess real consumer exposure. In this work, pesticide mobility in grapes was studied, by comparing their residual concentration in the skin with that of the whole grape. The efficiency of water washing to remove pesticides from grape skins was also evaluated.One variety of grapes from the Northern region of Portugal, Trajadura, sampled at two maturation periods of the 2001 crop, were analysed by a new validated methodology involving liquid chromatography with diode array detection.It was concluded that, although there were no significant differences between some pesticide levels found in the whole grape (skin and pulp) and in the grape skin, pyrimethanil was preferably found in the pulp, while metalaxyl was detected in the skin but not in the whole grape.The removal of pesticides from grapes by washing did not exceed 70% (procymidone). Never the less, it was concluded that consumer intake of the pesticides from grapes studied in this work should be significantly decreased as a result of water washing of the grapes.The concentration levels found for the pesticide residues were below both the Portuguese and the FAO Maximum Residue Levels (MRLs), thus causing no problems in terms of food safety.     

New Developments in Environmental Exposure Assessment in the EU Pesticide Regulatory Process

The paper discusses key aspects of the European Union (EU) regulatory policy for environmental exposure assessment of agricultural pesticide active substances (a.s.) in soil and water, which is examined in the context of the EU Authorisations Directive (91/414/EEC). For agricultural pesticide regulation within EU Member States (MS), the Authorisations Directive will gradually replace existing national systems. Discussion is concentrated on this directive, looking in particular at the Uniform Principles therein and the possible ways that these decision-making guidelines are being developed into a workable regulatory framework. The aim in this process of negotiated development involving the Member States, the Agrochemical Industry and the European Commission (EC), is to identify any questions or data requirements that will be needed for agricultural pesticides.     

柱萃取法测定农作物中的残留农药和土样中的二噁英

经均质的固体样品，根据含水量的不同和被测定组分的差异，分别与硅藻土、硫酸钠、弗罗里硅土等吸附剂混匀成可流动的粉末，装填成柱，然后以不同极性溶剂淋洗。多数情况下，所得溶液不需要进一步净化即可进行色谱分析．用极性溶剂如乙酸乙酯淋洗，选用任一种分散剂均能有效测定作物中的农药残留．在最佳条件下，一些有机磷、有机氯、氨基甲酸酯、拟除虫菊酯农药在某些粮谷、水果和蔬菜中以及多氯二苯并二恶英（ＰＣＤＤｓ）在土样中的添加回收率均大于８０％．实践证明该方法具有省时、省试剂、省净化程序等优点．