大米中氨基甲酸酯类农药的多残留检测

本文介绍一种大米中11种氮基甲酸酯类杀虫刺及其代谢产物的多残留快速测定方法。乙腈提取样品中农药,氨基固相萃取柱净化,甲醇和二氯甲烷(v/v,1/99)洗脱。液相色谱柱后衍生荧光检测器检测。对大米样品进行添加回收率实验,分别添加0．1mg/kg、0．5mg/kg、2mg/kg,回收率在71．9～98．2％之间,变异系数为2．78～10．6％。     

气质联用快速检测蔬菜中农药多残留

介绍一种蔬菜巾农药多残留快速测定方法。丙酮和二氯甲烷(v/v,3／2)的混合溶剂提取样品中农药,硅藻土和活性炭(m／m,7／3)的层析柱净化,丙酮和二氯甲烷(v/v,1/1)洗脱。气相色谱-质谱联用检测,采用选择离子扫描方式定性、定量。对黄瓜、甘蓝两种蔬菜样品进行添加回收率试验,分别添加0.2、0.1、0．05mg／kg,同收率在72％～108％之间,变异系数为2．45％～19．11％。     

气相色谱法分析土壤中的丁草胺残留

土壤中残留的丁草胺以石油醚-丙酮为提取溶剂,采用超声波提取、经液-液分配净化,经柱色谱预净化,由气相色谱(带ECD检测器)检测分析土壤中的丁草胺残留.发现土壤中丁草胺的添加回收率为81.98%～92.87%,变异系数为3.59%～5.65%,最低检测质量分数0.001 mg/kg.     

固相萃取-气相色谱法测定葱中啶虫脒的残留量

建立了葱中啶虫脒残留量的气相色谱检测方法. 样品经乙腈提取浓缩后,Florisil固相萃取柱净化,使用HP -5MS毛细管色谱柱进行气相色谱(ECD)分析,采用外标法定量. 在0.01～0.1 mg/kg添加水平范围内,葱样品中啶虫脒回收率为85.9%～106.8%,相对标准偏差为6.1%～7.9%,方法最低检出质量分数为0.01 mg/kg.     

甲草胺在花生中的残留分析及其稳定性

研究了甲草胺在花生中的残留分析方法和甲草胺的稳定性.样品以丙酮-水(体积比4:1)振荡提取,石油醚液-液分配,中性氧化铝柱层析净化,气相色谱测定.结果表明:甲草胺最小检出量为3.0 × 10-11g,花生中最低检测质量分数为0.008 mg/kg,花生添加质量分数0.1～1.0 mg/kg,回收率为78.10%～85.59%,变异系数为0.64%～3.70%;冷藏(4℃)条件下甲草胺标准溶液可贮存10～20 d,甲草胺花生提取液可贮存10～20 d.     

S-氰戊菊酯在甘蓝和土壤中的残留分析方法

确立了甘蓝和土壤中S-氰戊菊酯的残留分析方法.样本用丙酮/石油醚提取,中性氧化铝柱层析净化,气相色谱(ECD)测定.在甘蓝和土壤中的平均添加回收率分别为90.7%～98.3%和90.7%～97.0%;变异系数分别为4.8～7.6和3.8～5.0;最低检出浓度分别为0.0025mg/kg和0.00025mg/kg.     

两种分析食用植物油中抗氧化剂方法的比较

为了比较气相色谱/氢火焰离子化法(GC/FID)和高效液相色谱/二极管阵列法(HPLC/DAD)两种方法对植物油中BHA、BHT、TBHQ三种酚类抗氧化剂含量的检测。样品采用无水乙醇提取、冷冻离心后分别采用C18柱和HP-5毛细管柱进行分离,采用外标法进行定量测定。三种抗氧化剂在0～50 mg/L的浓度范围内线性关系良好。气相色谱法测定BHA、BHT、TBHQ三种成分的平均添加回收率在92.2%～95.1%之间,相对标准偏差在2.45%～3.08%之间,检出限分别为1 mg/kg、1 mg/kg和2 mg/kg。高效液相色谱法测定BHA、BHT、TBHQ三种成分的平均添加回收率在91.5%～94.3%之间,相对标准偏差在2.57%～2.92%之间,检出限分别为4 mg/kg、4 mg/kg和2 mg/kg。两种方法皆准确、灵敏、重现性好,适用于植物油中抗氧化剂的检测。     

气相色谱法同时测定玉米和土壤中乙草胺和2,4-滴丁酯残留

建立了用气相色谱法同时测定玉米植株、籽粒及土壤中乙草胺和2,4-滴丁酯的残留分析方法。玉米植株、籽粒中的乙草胺和2,4-滴丁酯经石油醚超声波提取,弗罗里硅土柱净化,土壤经二氯甲烷超声波提取,提取液浓缩至干后石油醚定容,气相色谱法电子捕获检测器测定。结果表明,乙草胺在玉米植株、籽粒、土壤中的添加回收率为85.0%～98.6%,相对标准偏差(RSD,n=3)为1.1%～3.4%;2,4-滴丁酯在玉米植株、籽粒、土壤中的添加回收率为83.0%～98.5%,相对标准偏差(RSD,n=3)为0.9%～2.4%。乙草胺和2,4-滴丁酯在样品中的最低检出浓度均为0.01 mg/kg。     

柑橘中除草醚残留量的气相色谱-质谱法测定

建立了柑橘中除草醚除草剂农药残留量气相色谱质谱检测方法。用乙腈提取试样中残留的药物,经中性氧化铝固相萃取小柱净化,采用气相色谱分离,质量选择检测器检测,外标法定量。除草醚农药在0.01μg/mL～5.0μg/mL浓度范围具有良好线性关系,线性相关系数在0.9989～0.9996,空白样品中添加0.01 mg/kg、0.05 mg/kg、0.1 mg/kg三个浓度,回收率在80.1%～104.3%之间,相对标准偏差在3.2%～14.3%之间。以信噪比为10计的方法检测限(LOD)为0.01 mg/kg,方法快速、简单,完全能够满足农药残留检测要求。     

GC-MS法测定白酒中氨基甲酸乙酯

改进检测白酒中氨基甲酸乙酯含量的气相色谱-质谱法(GC-MS)。样品经二氯甲烷提取,用旋转蒸发仪浓缩至近干,乙腈溶解,正已烷去除杂质,然后用气相色谱-质谱联用法检测。氨基甲酸乙酯标准浓度在0.1～1 mg/L范围内,线性关系良好,相关系数r达0.999。添加浓度为0.01～0.1 mg/kg时,回收率为77.7%～95.2%,相对标准偏差(RSD)在4.0%～6.3%之间,定量检出限低于0.01 mg/kg。改良后的GC-MS法操作简单快速、经济节约、灵敏度高。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。