石墨消解火焰原子吸收法测定茶叶中微量元素

本文研究了石墨消解仪与火焰原子吸收光谱仪(FAAS)联用测定茶叶中铜、锌、铁、锰4种微量元素的方法。经过对消解液和样品消解量的优化,确定了一个最适合茶叶样品消解的前处理方法。各元素的检出限分别为Cu0.50,Zn0.12,Fe0.25,Mn0.20mg·kg-1。回收率为94.8%~101%,精密度为0.5%~1.1%。该方法准确、快速、高效,是进行茶叶中微量元素测定的实用方法。     

原子吸收分光光度法测定花茶中微量元素的含量

以本地茶庄中常见的茉莉花,罗汉果花,牡丹花,月季花的花茶为样品,用浓硝酸-过氧化氢处理样品,原子吸收火焰法测定茶叶中Cu、Zn、Mg、Ca四种微量元素。所测定的花茶中含有丰富的人体必需的微量元素,采用此方法回收率在98.50%~101.82%之间,说明实验数据可靠,实验结果可信。     

原子吸收法测定多聚磷酸中微量金属元素含量

研究了多聚磷酸中微量金属元素含量的原子吸收法测定方法.进行了样品的前处理方法及条件、仪器条件的优化和准确度、精密度试验;建立了用铜试剂-MIBK系统对样品进行萃取,再用火焰原子吸收法测定多聚磷酸中痕量铅、镉、镍、铁和铜的方法.结果表明,铅、镉、镍、铁和铜的相对标准偏差均小于10%,回收率在95.0%～104.0%之间.分析方法快速准确,可满足定量分析的需要.     

火焰原子吸收光谱法测定绿色四氧化二氮中微量铁

提出用火焰原子吸收光谱法测定绿色四氧化二氮中铁的方法,确定了最佳仪器工作条件和样品处理方法。在选择好的试验条件下,测定铁的特征质量浓度为0.060mg/L,回收率为98.8%～101.4%,相对标准偏差小于2%。     

火焰原子吸收光谱法测定油漆筷子中铅含量

采用火焰原子吸收光谱法测定油漆筷子中铅含量.用0.07mol/L盐酸溶液萃取油漆筷子表面油漆涂层中的铅,其溶液用火焰原子吸收法进行测定含量.对油漆筷子样品进行分析时,铅含量在0～10.0mg/L时具有较好的线性关系,其回收率为97.90%～102.36%,方法具有较好的准确度.     

气相色谱串联质谱法用于茶叶中多种农药残留的分析检测

建立了茶叶中56种农药残留物质的检测,样品采用改进后的GB/T 23204-2008的方法处理,乙腈均质提取,旋转浓缩后过固相萃取柱净化,洗脱液经氮气吹至近干,乙酸乙酯定容,过膜后供GC-MS-MS分析。对茶叶样品进行不同水平的加标回收实验,得到物质的回收率在73. 2%～116%之间,RSD在2. 01%～10. 8%之间,线性相关系数在0. 99以上,方法的检出限为0. 01mg/kg。该方法灵敏度高、准确性好,可用于实际样品的分析检测。     

微波消解-火焰原子吸收法测定硅橡胶中的锡

采用微波消解系统,加入HNO3、HF或HNO3、HCl和HF消解硅橡胶样品,用火焰原子吸收法测定其中锡的含量.该方法简便、快速,相对标准偏差小于5%,回收率为89.55%～109.14%.     

火焰光度法快速测定钾肥中的钾含量

通过优化钾肥样品前处理条件,建立火焰光度法快速测定不同钾肥中钾含量的方法。样品经研磨、加水溶解、加热煮沸、定容、干过滤、稀释后,直接用火焰光度计测定。结果表明,火焰光度法的加标回收率为95.0%~103.0%,RSD为0.18%~0.50%,能够满足分析检测要求。此方法简便快速、准确可靠,可用于钾肥中钾含量的测定。     

微波消解-原子吸收光谱法测定葛粉中的微量元素

建立了用微波消解法处理样品、火焰原子吸收光谱法测定葛粉中Fe、Ca、Cu、Mn元素含量的方法,优化了微波消解、原子吸收测定的工作条件。建议的方法测得葛粉中Fe、Ca、Cu、Mn的含量分别为：27.83μg.g-1、272.46μg.g-1、6.98μg.g-1、9.45μg.g-1,加标回收率在96.9%～103.1%之间。建议的方法可用于实际葛粉样品中相应金属元素含量测定。     

茶叶中12种农药残留量的QuEChERS-液相色谱-串联质谱法测定

[目的]建立测定茶叶中12种农药残留量的液相色谱-串联质谱(LC-MS/MS)检测方法。[方法]茶叶样品经乙腈提取后,采用QuEChERS方法前处理,净化液经液相色谱-串联质谱测定,基质内标法定量。[结果]在0.001～0.1 mg/L范围内,12种农药的线性关系良好,相关系数r~2大于0.997,方法检出限为0.0003～0.01 mg/kg,定量限为0.001～0.04 mg/kg。阴性茶叶样品在低、中、高3个添加水平下的平均回收率为80.6%～106.6%,相对标准偏差为0.4%～8.2%。[结论]与传统的QuEChERS相比,该方法具有操作简单、快速、试剂用量少、回收率高、准确性强等特点,适合于茶叶中12种农药残留量的测定。     

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。