On-column partition cleanup of fatty extracts for organophosphate pesticide residue determination

A fast, single-step, and efficient partition between n-hexane and acetonitrile on ready-to-use, disposable mini-columns of Kieselghur-type material has been developed for the cleanup of fatty extracts for organophosphate (OP) pesticide residue determination by gas chromatography with flame photometric detection. Nine OP pesticides (diazinon, etrimfos, chlorpyrifos-methyl, pyrimiphos-methyl, chlorpyrifos, bromophos, bromophos-ethyl, malathion, fenitrothion) most commonly used for protection of stored cereals, oil seeds, and legumes were separated from up to 2.0 g lipidic material with recoveries between 80 and 107% at spiking levels ranging for the different compounds from 0.1 to 5.0 ppm.     

Determination of organochlorine and organophosphorus pesticide residues in eggs using a solid phase extraction cleanup

A multiresidue solid phase extraction (SPE) method for the isolation and subsequent gas chromatographic determination of nonpolar organochlorine and polar organophosphorus pesticide residues in eggs is described. The method uses an acetonitrile extraction followed by an SPE cleanup using graphitized carbon black and aminopropyl SPE columns. Organophosphorus pesticides are determined by gas chromatography with flame photometric detection. After further cleanup of the extract using Florisil SPE columns, organochlorine pesticides are determined by gas chromatography with electron capture detection. Studies were performed using eggs containing both fortified and incurred pesticide residues. The average recoveries were 86-108% for 8 fortified organochlorine pesticide residues and 61-149% for 28 fortified organophosphorus pesticide residues.     

Automated sample cleanup for pesticide multiresidue determination. I. Evaluation of solvent partitioning module

An automated continuous flow procedure is described that improves the cost effectiveness and precision of AOAC methodology for multiresidue pesticide determinations in nonfatty foods. Individual modules capable of performing automated solvent partitioning and automated column chromatography were constructed and integrated into a continuous flow system. Data are presented comparing the recoveries and precision for the determination of 8 pesticides (aldrin, dieldrin, p,p'-DDT, ethion, heptachlor epoxide, lindane, parathion, and ronnel) partitioned from 2 food crops (spinach and tomatoes) by both the manual and automated procedures.     

Automated sample cleanup for pesticide multiresidue analysis. Part II--Design and evaluation of column chromatography module

An automated, continuous flow system is described for Florisil column chromatography of pesticide residues from food extracts. Evaluation of the system using 5 common organochlorine and organophosphorus pesticides in 2 crop matrices demonstrates essentially no difference in recovery or precision between automated and currently used manual analyses. The automated procedure uses only 20% of the solvents and adsorbents used in the manual procedure and is 3 times faster.     

惠州农业土壤中有机氯农药残留的剖面分布特征

对惠州市6个样点的农业土壤剖面样品的17种有机氯农药残留量进行了测定,探讨了土壤剖面有机氯农药的残留现状和分布特征.结果表明,有机氯农药的检出率为100%,含量范围0.25～64.16tμg·kg-1.有机氯农药残留总量沿土壤剖面总的垂直变化趋势为随深度增加而下降.各组分在不同土壤深度具体变化特征因受多种因素影响而有所不同,HCHs峰值多出现在土壤亚表层,含量随深度变化幅度不大;DDTs在土壤深层的残留量远低于表层.从HCHs和DDTs的异构组成来看,DDTs残留主要是过去施用的残留物,HCHs可能与土壤新的林丹输入有关,需要进一步加强监管力度.     

Automated sample cleanup for pesticide multiresidue analysis. III. Evaluation of complete system for screening subtolerance residues in vegetables

An automated continuous flow sample cleanup system intended for rapid screening of foods for pesticide residues in fresh and processed vegetables has been developed. Recovery and precision data for 8 pesticides in each of 3 crops are compared for the automated and manual procedures. Average recovery for samples fortified with pesticides between 0.026 and 0.277 ppm was 98% for the automated system and 92% for the manual procedure. Average coefficient of variation was 6.6% for the automated system and 4.2% for the manual procedure. In another evaluation, the automated system gave an average recovery of 95% for 12 pesticides commonly found in imported foods; the manual procedure gave an average recovery of 91%. Thus, the results obtained so far indicate that the automated system for sample cleanup gives results comparable to those obtained by manual procedures.     

苹果中有机氯农药残留的超声波去除条件优化

中国是世界苹果第一生产大国,但中国苹果出口仅占世界贸易量的不足10%,其主要制约因素是安全性,其中农药残留是主要原因之一。论文采用响应曲面法对超声波去除苹果中有机氯农药残留的工艺条件（功率、时间、温度）及其交互作用进行了优化,并就超声波处理对苹果主要品质指标的影响进行了分析。结果表明：超声波去除苹果中有机氯农药残留的适宜工艺参数为：超声波功率为609.16 W,时间为70.46 min,温度为15.45℃,去除率可达到64.32%;超声波处理对苹果的硬度没有显著性影响;对苹果的总糖、总酸具有一定的显著性影响,但没有超出国家标准及主要出口国苹果标准的要求。超声波处理简单快速,能有效去除苹果中有机氯农药的残留,极大提高苹果的安全性,很容易和现有鲜果清洗、分级、打蜡生产线耦合链接,其产业化应用前景极为广阔。     

Determination of chlorinated pesticide residues in foods. II. Simultaneous analysis of chlorinated pesticide and phthalate ester residues by using AgNO3-coated Florisil column chromatography for cleanup of various samples.

A simplified method suitable for simultaneous analysis of chlorinated pesticide and phthalate ester residues in various foods was developed. Chemical residues were quantitatively extracted from fatty and vegetable samples with acetonitrile as follows: Chemical standard in 0.5 mL ethanol solution was added to 10 g homogenized sample. After 3 hr, pork and beef were extracted 3 times with 20 mL portions of acetonitrile. The acetonitrile layers were diluted with water and extracted with n-hexane. Rice samples were combined with 10 mL water, 5 mL acetonitrile and 1 mL ethanol and extracted 3 times with 20 mL portions of n-hexane. The n-hexane concentrate from each sample was submitted to AgNO3-coated Florisil column chromatography. The AgNO3 coating adequately adsorbed interfering coextractives. Extracts of fish and vegetable samples were separated into 2 fractions by the above column chromatography. Supplemental cleanup procedures were also developed to accurately determine phthalate esters eluted in the second fraction. Satisfactory gas chromatograms were obtained for most samples.     

紫外线降解水果中农药残留设备的设计与试验

为探讨高效降解水果中农药残留的方法,设计了紫外线降解农药残留的设备,利用紫外线照射水果表面,使水果中的农药残留发生降解。同时以乔纳金苹果和砀山酥梨为试验材料,研究了该设备的使用效果情况。研究结果表明：用波长为253.7 nm,有效强度为2243 μW/cm2的紫外光分别照射农药残留超标的苹果和梨3、2、1、0.5 min, 与未经照射的对照组相比,经处理的水果农药残留均大幅度下降;综合来看处理1 min的效果较好。苹果和梨处理1 min后残留乐果的降解率分别是57.40%、60.12%;残留氰戊菊酯的降解率分别是42.23%、41.25%;处理后的苹果和梨中的农药残留均远低于国家标准。     

免疫分析在农药残留检测中的应用和发展

通过分析免疫分析技术的基础——抗原抗体制备技术,进一步论述了主要免疫方法(放射免疫分析、酶免疫分析、荧光免疫分析、化学发光免疫分析等)的发展过程及其在农药残留检测中的应用。重点介绍了近年来免疫分析的新发展,尤其突出了免疫分析和理化分析联用技术这一痕量分析的新主流。探讨了免疫分析技术存在的问题和免疫分析的未来发展趋势。     

Evaluation of an automated gel permeation cleanup and evaporation systems for determining pesticide residues in fatty samples

The AutoVap 600 system, used in conjunction with an automated gel permeation chromatography (GPC) instrument, automatically collects and evaporates the effluent from the GPC column, dissolves the residue in a fixed volume of desired solvent, and quantitatively transfers it to a sealed vial. This system was evaluated and found to automate efficiently the cleanup of butterfat for pesticide residue analysis. Quantitative recoveries were obtained for each of 4 pesticides fortified in butterfat and cleaned up through the system and for 12 pesticide standards in the absence of sample matrix collected through the system. After loading, the system operates unattended and will automatically prepare up to 23 individual fat samples for determination by gas chromatography without additional cleanup.     

Assisted distillation cleanup of pesticide residues in animal fats: new beadless distillation tube

A new assisted distillation tube has been developed which contains no glass beads or glass wool. The sample is injected into the top of the tube, and a septum is not required. Large ground-glass joints (10/19) are used at the gas inlet and at the Florisil trap connection for maximum strength. Existing assisted distillation apparatus was easily modified to accept the new tubes. Recoveries of 9 organochlorine pesticides from butter and cattle fat ranged from 87 to 104% at a tube temperature of 230 degrees C and a nitrogen flow rate of 250 mL/min. No significant change occurred in recoveries of 8 of the 9 pesticides after 85 uses of the beadless tube. Only the recovery of HCB from butter decreased, from 95 to 80%, after 51 runs. The new tube was compared with the Unitrex glass bead-packed concentric tube at flow rates of 230, 400, and 600 mL nitrogen/min. Recoveries from the Unitrex tube were similar to those of the beadless tube for all pesticides except DDT which was significantly lower, indicating incomplete distillation at 250 mL/min and possible partial breakdown at 400 and 600 mL/min. A procedure is introduced for pressurized solvent washing of distillation tubes. This procedure is more efficient than vacuum washing.