要实事求是地看待化学农药

不久前,中国科学院院士李正名表示,在日益重视生态环境保护的今天,生物防治等一些有益环境的防治措施固然是发展方向,但这并不意味着可以偏废化学农药的使用。更何况已出现了用高新技术开发的新型绿色农药。在全球每年320亿美元销售量的农药中,生物农药仅占1.5％。其主要原因是目前的生物农药的药效来的比较慢,真正对付突如其来的虫灾,化学农药仍是主流。     

农药化学:魔鬼还是天使

本文简介了农药化学的研究范围,以杀虫剂为例评述了化学农药在中国的发展过程及发展方向。     

农药残留与食品安全——由中日间的“毒饺子”事件引发的思考

近年来,农药残留和食品安全问题成为备受关注的研究领域。本文从中日间“毒饺子”事件引发的社会问题,简单介绍了农药与食品安全的关系,概述了甲胺磷农药的结构、性质和致毒机理,介绍了食品中化学农药残留的种类、农药残留污染样品的处理以及减少农药残留污染的对策等内容,并对该领域的发展作了展望。     

农药,农药污染与环境

农药(或称为化学农药)是指用于防治危害农作物及农副产品的病虫害、杂草与其他有害生物(包括卫生害虫)的化学品统称.农药的发现、生产和应用是本世纪化学家对人类做出的巨大贡献之一.我们用化学方法合成农药,农药又促进了化学(尤其是有机合成)的发展.对于农药我们并不陌生,它已从单一的农作物应用而变为多种效能.农药已走入千家万户,我们用卫生杀虫剂杀灭蚊蝇、蟑螂、老     

影响气相色谱法检测蔬菜中农药残留量的因素探讨

正化学农药是当前必不可少的生产资料,有效地防治了农作物病虫害,显著地提高了农副业经济效益。但随着农药的大量使用,蔬菜水果中农药残留问题日益严重,威胁着每个人的健康,食品中农药残留问题已经成为人们关注的焦点[1]。目前,气相色谱法因其检测精确度高、重复性好,是水果、蔬菜、谷物中农药残留定量分析的主要方法[2-6]。但是果蔬品种繁多,基质多种多样,农药性质不一,前处理步骤较多,因此如何精准高效地检测农药残留量种类     

超高效液相色谱-串联质谱法测定茶叶中5种农药残留量

我国是世界茶叶主要生产国和出口国之一,尤以绿茶、乌龙茶、普洱茶、花茶等闻名于世。然而为了防治茶树病虫害,各种化学农药在茶园中被广泛使用,不可避免地导致茶叶中的农药残留超标,茶叶中农药残留问题已成为茶叶质量安全的焦点之一。欧盟和日本作为我国茶叶出口的两大市场,均对茶叶制定了苛刻的农药残留限量标准[1-2]。而我国的相关标准相对滞后,建立和完善茶叶中多种农药残留同时检测的分析方法尤为迫切。     

自然水体中3种固相物质吸附有机氯农药的动力学特征

研究了自然水体中生物膜、 悬浮颗粒物和表层沉积物3种典型固相物质对有机氯农药的吸附动力学特征. 研究结果表明, 有机氯农药在3种固相物质上的吸附动力学过程可分为快吸附阶段和慢吸附阶段. 准二级动力学模型较好地描述了三者对有机氯农药的吸附动力学过程. 吸附平衡时, 3种固相物质对有机氯农药吸附量的大小与它们的有机质含量顺序一致, 即, 生物膜>悬浮颗粒物>表层沉积物; 而在吸附初期阶段, 有机质含量最低的表层沉积物对有机氯农药的吸附速率最快, 吸附量的波动变化幅度最大, 其次为悬浮颗粒物和生物膜.     

我国化学农药的进展

在毛主席革命路线指引下,在无产阶级文化大革命和批林批孔运动的推动下,我国农药工业和农林业病、虫、草害防治工作蓬勃发展,形势大好。目前在发展高效、低毒、低残留农药、研制防治难治的重大农林病虫害新药剂和大力开展水旱田除草剂的使用方面都做了不少工作,取得较大的成效。由于我国农药事业的发展,使我国重大农林病虫危害受到控制,农林业增产得到保证,农林化学除草得以逐步实现,把我国农药化工和农林植物保护工作提高到新的水平,为社会主义革命和社会主义建设作出了贡献。我国农民采用以砷、汞、硫黄等矿物和烟草、除虫菊、黄藤等植物为原料配制杀虫、杀菌药剂来防治农作物病虫害已有悠久的历史。但是,我国化学农药工业     

中国农药自主创制

农药是农业发展的保障,农业的发展离不开它。中国是农业大国,农药创制必须得依靠自己。中国农药的发展与中国农业现代化发展同频共振。新农药创制是一个系统工程,需要各个学科都能达到高科技水平。当今,中国的农药研究已经站在一个更高的起点和水平上,用自己原创的理论、方法、手段和靶标进行农药创制;一定程度上,中国的农药研究在某些领域已经开始引领全球农药发展。结合新中国成立后我国农药的发展状况,本文总结了70个自主创制农药产品。依据新创制农药的类型、创制时间、创制单位、主要作用对象、作用方式、作用机理等,概述了中国新创制农药的发展历程。     

吡咯异构体的电子结构与杀虫活性研究

长期以来,农药的化学结构与生物活性--即药效之间的关系一直是化学家和生物学家致力研究的方向[1].自1964年Hansch和Fujita提出多参数法[2],同年Free和 Wilson提出了相加模型法[3],以及稍后发展起来的分子轨道法以来,农药化学结构与生物活性的定量关系的研究发展到了一个新的阶段.     

Sample treatment and determination of pesticide residues in fatty vegetable matrices: A review

A demanding task in pesticide residue analysis is yet the development of multi-residue methods for the determination of pesticides in vegetables with relatively high fat content (i.e. edible oils and fatty vegetables). The separation of pesticides and other chemical contaminants from high-fat food samples prior to subsequent steps in the analytical process is yet a challenging issue to which much effort in method development has being applied. This review addresses the main sample treatment methodologies for pesticide residue analysis in fatty vegetable matrices. Even with the advent of advanced hyphenated techniques based on mass spectrometry these complex fatty matrices usually require extensive sample extraction and purification. Current methods involve the use of one or the combination of some of the following techniques for both the sample extraction and clean-up steps: liquid-liquid partitioning, solid-phase extraction (SPE), gel-permeation chromatography (GPC), matrix solid-phase dispersion (MSPD), etc. An overview of methods developed for these contaminants in fatty vegetables matrices is presented. Sample extraction and purification techniques are discussed and their most recent applications are highlighted. This review emphasizes that sample preparation is a critical step, but also the determination method is, and cannot be treated separately from sample treatment. In recent years, the appearance and use of new, more polar pesticides has fostered the development of liquid chromatography/mass spectrometry (LC-MS) besides gas chromatography. The main features of LC-MS for the analysis of multi-class pesticides in fatty vegetable samples will be also underlined, with an emphasis on the multi-class, multi-residue strategy and the difficulties associated.     

再论化学元素周期表的形成和发展

以时间为序,将化学元素周期表的发现和发展分为萌芽、突破、发展和展望四个阶段,引用主要史实文献将其串联起来进行解读,以利于周期表的深入教学,并作为相应科学研究之参考。     

Decontamination of pesticide packing using ionizing radiation

The Brazilian agriculture activities have consumed about 288,000 tons of pesticides per year conditioned in about 107,000,000 packing with weight of approximately 23,000 tons. The discharge of empty plastic packing of pesticides can be an environmental concern causing problems to human health, animals, and plants if done without inspection and monitoring. The objective of this work is to study the ionizing radiation effect in the main pesticides used in Brazil for plastic packing decontamination. Among the commercial pesticides, chlorpyrifos has significant importance because of its wide distribution and extensive use and persistence. The radiation-induced degradation of chlorpyrifos in liquid samples and in polyethylene pack was studied by gamma radiolysis. Packing of high-density polyethylene (HDPE) three layer coextruded, named COEX, contaminated with chlorpyrifos, were irradiated using both a multipurpose Co-60 gamma irradiator and a gamma source with 5000 Ci total activity Gamma cell type. The chemical analysis of the chlorpyrifos was made using a gas chromatography associated to the Mass Spectrometry—GCMS from Shimadzu Model QP 5000. Gamma radiation was efficient for removing chlorpyrifos from the plastic packing, in all studied cases.     

也论化学元素周期表的形成和发展

In the time order, the author proposes that the discovery and development of the periodic table of chemical elements are divided into four stages:point→1D→2D→3D. This article cites the main historical facts and documents available to unscramble the above four stages, which will facilitate the teaching and scientific research of the periodic table.     

Product range,properties, and application of fluoropolymers manufactured in Kirovo-Chepetsk Chemical Industrial Complex

The main historical stages of development in the USSR of industrial production of fluoroplastics and organofluorine materials are outlined. Physical, chemical and biological properties of fluoroplastics and fluoroelastomers are described. Examples of efficient application of fluoropolymers in chemical and natural gas industry, power production, and medicine are cited. The review is intended for specialists in fluoropolymers application.     

Food safety assurance using methods of chemical analysis

A review of state-of-the-art methods of sample preparation and chemical analysis for the control of contaminants in foodstuffs and food raw materials is presented. The main achievements and performance characteristics of methods for the determination of pesticides and veterinary drugs, their metabolites, natural toxins, trace amounts of chemical elements, first of all toxic, allergens, food additives, and contaminants from packaging materials in foodstuffs and for the identification of falsifications by methods of chemical analysis are considered.     

Analysis of multiple pesticide residues in tobacco using pressurized liquid extraction, automated solid-phase extraction clean-up and gas chromatography-tandem mass spectrometry

A new method was developed for the analysis of pesticide residues in tobacco. The objective was to significantly increase the number of samples that can be processed by the laboratory and to enable the extension of the current coverage to additional pesticides. A new analytical approach was therefore defined based on two main axes, the automation of the sample preparation and the selectivity of the analyte detection using tandem mass spectrometry. This latter aspect reduces the stringency of the requirements placed on the clean-up of the extracts and on the chromatographic resolution when less selective detectors are used. The extraction of the analytes from the matrix is performed using the pressurized liquid extraction technique. Tobacco samples are extracted at elevated temperature and pressure (100 C and 100 atm; 1 atm = 101,325 Pa) using acetone as an extraction solvent. The resulting extract is then concentrated using a Vortex evaporator. Three different solid-phase extraction (SPE) procedures, adjusted to the chemical properties of the different active ingredients to be measured, are applied to the concentrated extract, thus leading to three extract fractions. The first fraction contains such main classes of active ingredients as organohalogenated and 2,6-dinitroaniline compounds while the second one collects the organophosphorus and acylalanines residues; these two fractions are analyzed by capillary gas chromatography coupled to tandem mass spectrometry using negative chemical ionization and electron impact ionization in the positive mode, respectively. The third extract fraction gathers the N-methylcarbamates residues which are analyzed by HPLC with post-column derivatization and fluorescence detection. The different sample preparation stages from extraction to SPE clean-up have been automated through the use of recent analytical technologies. In combination with the analysis by tandem mass spectrometry, this provided a potential for a high sample throughput.     

Interpretation and modelling of environmental behaviour of diverse pesticides by revealing photodecomposition mechanisms

Pesticides are commonly applied agrochemicals, however their long-term chemical behaviour and environmental fate involving degradation processes have not been studied thoroughly and extensively yet. As photolytic decomposition might be regarded as one of the key factor in determining environmental behaviour of pesticides, it is of high relevance to have comprehensive knowledge on characteristics of pesticide degradates having potential harmful biological effects. Toxicity of the examined pesticides is well known, however scarce information is available on their natural degradation processes, as well as the quality, structure and biological impact of the decomposition products.Our study is focused on revealing specific details of photolytic degradation behaviour of 3 frequently applied pesticides and mapping the entire decomposition mechanisms.Special, immerseable, low pressure mercury-vapour lamp was applied to induce photolytic transformation, which was followed by TLC and GC. The pesticides and the obtained products were identified by using GC-MS technique. The structure identifications were based on the interpretation of the fragmentation pathways.All the pesticide studied proved to be photosensitive and major stages of the UV-degradation pathway were found to be the loss of alky-groups, cleavage of the chloro-group and the hydroxylation, scission of N-alkyl groups and decarbonylation.In contrast to previous studies, different and specific degradates and end-products have been established, and the existence of alternative conversion pathways was revealed.