几种分离技术在农药残留分析中的应用

本文介绍了样品现代前处理技术加速溶剂萃取(ASE)、超临界流体萃取(SFE)、固相萃取(SPE)、固相微萃取(SPME)、凝胶渗透色谱(GPC)的原理及其在农药残留分析中应用情况。     

固相微萃取技术进展及其在农药残留分析中的应用

固相微萃取技术是一种无需溶剂、方便快速的样品前处理技术。本文介绍了固相微萃取在设备构造、萃取纤维及涂层材料的开发等方面的发展情况,并对其在农药残留分析中的应用进行了总结。     

固相微萃取技术的原理及应用

本文所介绍的固相微萃取技术是一项无溶剂样品制备方法，其原理是利用分析组分在样品基质提取与提取剂中的分配不同，从而达到分离目的，具有简便，经济，不使用溶剂等优点，并且能做到提取，净化浓缩和ＧＣ上进样分析同步完成，本文还对固相微萃取的装置，工作程序及应用作了介绍。     

固相萃取-气相色谱法测定水体中29种农药的残留量

建立了水体中29种农药的固相萃取-气相色谱检测方法。以Envi-18固相萃取小柱提取水样中的各种农药,上样体积为200 mL,洗脱溶剂为正己烷-丙酮(1∶1,体积比)。在添加水平为0.1、1.0和10 μg/L时,水样中29种农药的添加回收率为60%~111%,相对标准偏差(RSD)为1.2%~6.4%,方法的检出限(LOD)为5~50 ng/L。所建立方法准确、灵敏、快速,符合水体中多种农药残留检测分析的要求,且对水体中低浓度残留农药的检测效果较好。     

固相萃取技术在农药残留测定中的应用

本文介绍了固相萃取技术的原理和使用,应用该技术测定了柑桔中唑螨酯的残留量。     

固相萃取-气质联用测定茶叶中的26种农药残留

本文研究了固相萃取-气质联用方法测定茶叶中农药残留的方法。用乙睛从茶叶中提取,固相萃取净化26种农药残留,运用GC/MS进行分析。以内标法定量,加标浓度分别为0.01、0.10、1.00mg/kg时,回收率在75.06%~108.26%之间,相对偏差≤10%。方法检出下限为0.01~0.05μg/mg,用该方法可实现对茶叶中农药残留的检测。     

固相萃取-高效液相色谱法同时检测土壤中4种咪唑啉酮类除草剂残留

建立了一种以SAX固相小柱萃取和高效液相色谱(HPLC)法同时检测土壤中咪唑烟酸、甲基咪草烟、咪草酸甲酯和咪唑乙烟酸4种咪唑啉酮类除草剂残留的方法。考察了不同提取剂、pH、固相萃取(SPE)小柱和淋洗液体积等因素对回收率的影响。结果表明:采用SAX固相萃取小柱,以V(乙腈)∶V(水)=5∶3混合溶液为提取剂,6 mL甲醇为淋洗液时,在pH=3条件下,样品的提取及净化效果较好。淋出液浓缩后用甲醇定容,过滤膜后经HPLC检测。添加回收试验结果表明:在0.02~0.5 mg/kg添加水平下,4种除草剂的平均回收率在86%~109%之间,相对标准偏差(RSD)≤3.3%(n=5)。咪唑烟酸、甲基咪草烟和咪唑乙烟酸在土壤中的定量限(LOQ)均为0.01 mg/kg,咪草酸甲酯的LOQ为0.02 mg/kg。     

固相萃取-高效液相色谱法测定水果蔬菜中的赤霉酸残留

采用固相萃取-高效液相色谱(SPE-HPLC)法建立了快速、准确检测果蔬中赤霉酸(GA3)残留量的方法。样本采用丙酮-水(5 ∶ 1,体积比)进行超声提取,经石油醚脱色、乙酸乙酯萃取、HyperSep C18固相萃取小柱净化(以1 mL甲醇为净化剂,以1 mL水为活化剂,上样液为1 mL 10%的甲醇,以5 mL 40%甲醇为洗脱剂),用HPLC检测,外标法定量。结果表明,GA3在0.05~10 mg/L范围内线性关系良好,相关系数 r =0.999 7,检出限(LOD)为0.012 mg/kg。用所建立的方法抽检了18种市售果蔬样品,在1 mg/kg添加水平下的回收率在90.58% ~99.35%之间,相对标准偏差在1.25%~8.67%之间。该方法稳定、准确,适用于果蔬中GA3的残留检测。     

全自动在线顶空固相微萃取-气相色谱-质谱联用检测水样中24种常见农药

为提高环境水体中微量农药检测方法的效率和灵敏度，建立了全自动在线顶空固相微萃取-气相色谱-质谱联用 (HS-SPME-GC/MS) 检测水中24种常见农药的方法，考察了萃取针涂层材料、最佳萃取温度、萃取时间和解吸时间对萃取效果的影响，优化了固相微萃取基质中离子浓度等条件。结果显示:24种目标农药的浓度-响应线性关系良好，决定系数 (R2) 均大于0.9950，方法检出限 (LOD) 为0.25~5.0 μg/L，定量限 (LOQ) 为0.5~10 μg/L，回收率为86%~117%，相对标准偏差 (RSD) 均小于18%。本方法适用于水样中微量有机磷、氨基甲酸酯、有机氯及菊酯等类型常见农药的快速定性定量检测，具有便捷高效、灵敏度高等优点，可用于环境水体中农药投毒案件物证的检验鉴定。     

分散固相萃取-气相色谱法测定含油食品中亚胺唑的残留

建立了检测含油类食品(核桃、花生油和干辣椒粉)中亚胺唑残留的分散固相萃取-气相色谱分析方法。样品中的亚胺唑经乙腈提取,N-丙基乙二胺吸附剂(PSA)和十八烷基键合硅胶吸附剂(C18)混合分散固相萃取净化剂净化,气相色谱法测定,基质标准曲线-外标法定量。结果显示:在0.005~10 mg/L范围内,亚胺唑的色谱峰面积与其质量浓度间呈良好的线性关系,相关系数r > 0.99;定量限为0.05 mg/kg。在0.05、0.1和1 mg/kg添加水平下,亚胺唑在核桃、花生油及干辣椒粉基质中的添加回收率为82%~107%,相对标准偏差为3.0%~6.3%。方法各项性能均能满足对含油食品中亚胺唑残留分析的要求。     

Hymenopteran Parasitoids on Fruit-infesting Tephritidae (Diptera) in Latin America and the Southern United States: Diversity, Distribution, Taxonomic Status and their use in Fruit Fly Biological Control

We first discuss the diversity of fruit fly (Diptera: Tephritidae) parasitoids (Hymenoptera) of the Neotropics. Even though the emphasis is on Anastrepha parasitoids, we also review all the information available on parasitoids attacking flies in the genera Ceratitis, Rhagoletis, Rhagoletotrypeta, Toxotrypana and Zonosemata. We center our analysis in parasitoid guilds, parasitoid assemblage size and fly host profiles. We also discuss distribution patterns and the taxonomic status of all known Anastrepha parasitoids. We follow by providing a historical overview of biological control of pestiferous tephritids in Latin American and Florida (U.S.A.) and by analyzing the success or failure of classical and augmentative biological control programs implemented to date in these regions. We also discuss the lack of success of introductions of exotic fruit fly parasitoids in various Latin American countries. We finish by discussing the most pressing needs related to fruit fly biological control (classical, augmentative, and conservation modalities) in areas of the Neotropics where fruit fly populations severely restrict the development of commercial fruit growing. We also address the need for much more intensive research on the bioecology of native fruit fly parasitoids.     

Brief Guide for Authors

正Journal of Arid Land(JAL)is an international journal(ISSN 1674-6767;CN 65-1278/K)for the natural sciences,sponsored by the Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences and Science Press.It is published by Science Press and Springer-Verlag Berlin Heidelberg bimonthly.JAL publishes original,innovative,and integrative research from arid and semiarid regions,ad     

The parasitoid complex ofLiriomyza cicerina on chickpea (Cicer arietinum)

Liriomyza cicerina (Diptera: Agromyzidae) is an important pest on chickpea in Turkey. The objective of this study was to determine the parasitoids and rates of parasitism ofL. cicerina on chickpea (Cicer arietinum L.) during the 2005 and 2006 seasons in ?anl?urfa province, Turkey. Leaves with mines were sampled weekly and kept in the laboratory to observe and count emerging leafminer and parasitoid adults. Eight parasitoid species were collected: the braconidsOpius monilicornis Fischer andOpius tersus Foerster and the eulophidsDiaulinopsis arenaria (Erdös) andNeochrysocharis formosa (Westwood), which occurred in both the winter and summer seasons;Diglyphus crassinervis Erdös,Neochrysocharis ambitiosa Hansson,Neochrysocharis sericea (Erdös) andPediobius metallicus (Nees), which occurred only in the summer growing areas.Diaulinopsis arenaria was the predominant parasitoid with 4–7.7% parasitism rate whileN. ambitiosa andO. monilicornis were the second and third most predominant species. The results of these trials show that sinceDia. arenaria occurred throughout every season, it could potentially be used for control of the leafminerL. cicerina.     

Plant–herbivore asynchrony necessitates augmentative releases of the exotic beetle,Zygogramma bicolorata,to enhance the biological control of P arthenium hysterophorus

Systematic information on the quantitative impact of Z ygogramma bicolorata on the biology of P arthenium hysterophorus is crucial as the seeds of this weed continue to germinate from the accumulated soil seed bank throughout the year in the form of different germinating flushes, while the activity of the beetle ceases during winter as it enters diapause. Therefore, plant–herbivore interactions need to be explored to develop predictions of the overall impact of the introduced beetle on the weed. The findings revealed that defoliation by Z . bicolorata had a significant impact on the plant height, density and flower production in flushes F ₃, F ₄ and F ₅, but not in F ₁ and F ₂ that exhibited longer periodicity, profuse branching, a longer flowering period and maximum flower production and contributed mostly to the existing seed soil bank. Therefore, total depletion of the existing soil seed bank was not possible. Consequently, the effect of augmentative field releases of laboratory‐reared beetles was explored on F ₁ and F ₂ in February for three consecutive years (2011–2013). Before initiating the trial, random soil samples were taken from the plots that were assigned to the paired treatments (i.e. with the beetle and without the beetle [insecticide‐treated]) and it was found that the seed bank in those samples did not differ. The single release of Z . bicolorata adults at five per plant at the six‐leaf stage significantly reduced the soil seed bank, compared to without the biocontrol agent, irrespective of the flushes at the end of the season.     

Effects of the saprophytic leaf mycoflora on growth and productivity of winter wheat

The effects of the saprophytic mycoflora and its interference with cereal aphids on growth and yield of winter and spring wheat was studied in field experiments in 1980, 1981 and 1982.Yields varied between 5000 and 8000 kg dry matter of kernels per ha. The effect of the saprophytic mycoflora on yield was determined in different treatments: A) no control measures against cereal aphids and saprophytic and necrotrophic fungi, B) no control of cereal aphids, control of saprophytic and necrotrophic fungi, C) control of cereal aphids and control of saprophytic and necrotrophic fungi, D) control of cereal aphids and stimulation of saprophytic mycoflora and E) control of cereal aphids, no control of saprophytic and necrotrophic fungi nor stimulation of saprophytic mycoflora.Considerable differences in top densities of saprophytic mycoflora (10 times as large in A and D as in B and C) were determined. The consequences of these differences for the growth and productivity of wheat were minor. A negative effect of saprophytic mycoflora on the yield could not be detected in 1981 and 1982, whereas a small positive significant effect was found in 1980. This stimulation may have been due to competition between necrotrophic fungal pathogens and saprophytic mycoflora. As a result of favourable weather conditions necrotrophic fungal pathogens were very numerous in 1980 and could form an important yield reducing factor. Yield levels may effect the importance of the necrotrophic and saprophytic mycoflora as yield reducing factors. Additionally, in the presence of aphid honeydew captafol was found to be relatively ineffective against saprophytic fungi.     

Relationship Between Production of the Phytotoxin Prehelminthosporol and Virulence in Isolates of the Plant Pathogenic Fungus Bipolaris sorokiniana

A gas chromatographic method was developed to quantify the phytotoxin prehelminthosporol, which is a sesquiterpene metabolite of the plant pathogen Bipolaris sorokiniana. The toxin was extracted from mycelium or culture filtrates, pre-cleaned using solid phase extraction, and analyzed by gas chromatography as a trimethylsilyl-derivative. The detection limit of the method was 5ngl^–1 (signal to noise ratio 4:1) which corresponds to ca. 15ng prehelminthosporol per mg dry weight of mycelium or 15ng prehelminthosporol per ml culture filtrate. The total amount of prehelminthosporol (mycelium plus culture filtrate) increased with cultivation time when examined in six isolates of B. sorokiniana after 6, 9, 12 and 15 days of incubation. The screening experiment of 17 isolates for prehelminthosporol production after 8 days of incubation revealed significant differences in the toxin production between the isolates. The isolates with low toxin production had lower virulence towards barley roots compared to those with higher production of the toxin. However, the virulence did not increase with prehelminthosporol level among the high producing isolates. Prehelminthosporol was also analyzed in a number of related Bipolaris and Drechslera species. In addition to B. sorokiniana, three out of six Bipolaris species (B. setariae, B. zeicola, B. victoriae) produced prehelminthosporol, which indicates that ability to produce prehelminthosporol is conserved among closely-related Bipolaris species.     

Effect of botanical insecticides and bacterial toxins on the gut enzyme of the rice leaffolderCnaphalocrocis medinalis

The effect of botanical insecticides and bacterial toxins on gut enzyme activity of larvae of the rice leaffolderCnaphalocrocis medinalis (Guenée) (Insecta: Lepidoptera: Pyralidae) was investigated. Gut enzyme activities were affected by botanical insecticides and bacterial toxin individually and in combination. When fed a diet of rice leaves treated with botanical insecticides and bacterial toxins, in bioassays the activities of gut tissue enzymes — acid phosphatases (ACP), alkaline phosphatases (ALP) and adenosine triphosphatases (ATPase) — of rice leaffolder larvae were affected. When combined, the effect was more severe at a low concentration. Larvae that were chronically exposed to botanical insecticides and bacterial toxins showed a reduction in weight (59–89%) and exhibited a significant reduction in ACP, ALP and ATPase activities. The combination ofBacillus thuringiensis kurstaki and botanical insecticides caused a decrease of twofold in enzyme activity even at reduced concentration. A synergistic effect was found when botanical insecticides and bacterial toxins were combined at low doses. These effects were most pronounced in early instars. Clear dose-response relationships were established with respect to enzyme activity. In conclusion: (i) biopesticides are relatively safe and biodegradable; (ii) a synergistic effect of botanical insecticides and bacterial toxins was found; (iii) less expensive, readily available and naturally occurring biopesticides could be an alternative for organic and inorganic pesticides in controlling RLF. http://www.phytoparasitica.org posting Sept. 28, 2004.