火焰原子吸收光谱法快速测定车用汽油中的锂

建立有机稀释-火焰原子吸收光谱法测定车用汽油中锂元素的含量的方法。样品经碘-甲苯溶液处理样品,用氯化甲基三辛基铵-甲基异丁基甲酮溶液稀释,火焰原子吸收光谱法进行测定。标准曲线相关系数均≥0.999,加标回收率:91.5%~110.3%,RSD均在5%以内。方法简便、准确、成本低廉,可用于车用汽油中锂元素含量的检测。     

无稳定剂悬浮液进样——火焰原子吸收光谱法测定菠菜中的锌、锰、钾、钙

在无稳定剂条件下直接用蒸馏水制成菠菜样品的悬浮液,用SrCl2和CsCl消除相关干扰,在磁力搅拌下进样,应用标准曲线法在同一溶液中利用空气-乙炔火焰原子吸收光谱法测定Zn、Mn、K、Ca等4种元素含量。结果表明,菠菜中富含Zn、K、Ca及Mn。以无刺种菠菜叶样品为例,详细研究了干扰及其消除的条件,考察了方法的准确度和精密度。试验表明,在选定的条件下,菠菜中各元素间相互不干扰测定。方法的加标回收率在90.5%~101.5%之间,相对标准偏差在0.2%~1.1%之间(n=3),测定结果准确可靠。     

微波消解-火焰原子吸收光谱法测定毛华菊中金属元素

采用微波消解法对草药毛华菊进行消解,并用火焰原子吸收光谱法对其中的Zn、Mg、Ca、Fe等4种元素的质量分数进行测定。在最优实验条件下测得Zn、Mg、Ca、Fe各元素的质量分数分别为88.87、3 462.7、10 413.3、1 267.4μg/g。各元素的相关系数为0.992 2~0.999 8,RSD为0.17%~1.99%,加标回收率为94.40%~103.90%。各元素的检出限为0.001 7~0.069 0μg/m L。     

微波消解-FAAS检测婴幼儿奶粉中重金属元素

通过微波消解-火焰原子吸收光谱法(FAAS)检测婴幼儿奶粉样品中的铅、铬、铜、钴、锌5种重金属元素含量。对仪器工作条件进行优化,测定的相对标准偏差(RSD)为0.036 1%~5.647%,回收率为97.2%~105.3%。     

原子吸收光谱法测定四氧化三锰产品中多种杂质元素

用盐酸溶解样品 ,火焰原子吸收光谱法测定四氧化三锰中铁、钙、镁、钾、钠 ,石墨炉原子吸收光谱法测定其中的铬。对测定条件进行了试验 ,找出了最佳溶样方法和酸度 ,并对共存元素的干扰及排除进行试验 ,获得了满意的效果。该法简便、快速、准确 ,样加标回收率为 98.6%～ 1 0 9.6%之间 ,相对标准偏差为 1 .61 %～ 4.96%之间 ,倍比实验、标准曲线法和标准加入法结果相吻合 ,适用于四氧化三锰样品中铁、钙、镁、钾、钠、铬元素的分析。     

原子吸收分光光度法测定低品位铜的实验研究

火焰原子吸收分光光谱法测定铜的实验方法,基于元素的基态原子蒸汽对同种元素的原子的特征谱线的共振吸收作用来进行定量分析。火焰原子吸收光谱法,具有操作简单,分析速度快,干扰少、选择性比较好,准确度高等优点。此方法应用增大称样量,调节燃烧头的旋转角度,改变溶液的稀释倍数,提高溶液的吸光值,并引用火焰法可准确的测定低含量铜的矿样。此方法操作简单,易于掌握,避免了用极谱仪测样污染环境和滴定分析法终点不明显、难判断、误差大的缺点,提高测定准确度,是一种可靠的分析方法。     

原子吸收光谱法测定锌单标准样品与含锌多金属混合标准样品中锌浓度的探讨

原子吸收光谱法技术发展成熟,已广泛应用于定量测定试样中金属元素。本文采用原子吸收光谱法与电感耦合等离子体质谱法分别对不同的锌单标准样品及含锌多金属元素混合标准样品中的锌进行定量分析。结果显示对于锌的多金属混标,采用火焰原子吸收光谱法进行测定时,往往无法获得较为理想的实验结果,实验值偏离真值。电感耦合等离子体质谱法,干扰少,灵敏度高,采用该方法对相同的标准样品进行测定,实验测定值落在真值范围内。结果表明锌混标中的其他并存金属元素极易对锌的火焰原子吸收光谱法测定结果产生干扰。采用火焰原子吸收光谱法进行锌的标准物质测定时,应尽量使用锌单标准物质。若使用多金属元素混合标准样品,则需采取如螯合萃取等方法以排除干扰。     

塞曼无火焰原子吸收法测定高纯硝酸钡中的杂质

前言高纯硝酸钡中微量“铬、钴、铜、锰、铁、钠”的测定国内尚无标准分析方法。近年来原子吸收光谱法已发展成为一种重要的痕量分析手段,用火焰原子吸收法直接进行样品中各元素的测定比较困难,为了排除干扰和提高分析灵敏度,曾试验了以有机溶剂APDC/MiBK──火焰原子吸收分光光度法。由于样品中被测元素含量甚微,其方法的灵敏度和精度均较差,这对分析结果将带     

精四氯化钛中铁含量的测试方法研究

为了能更准确的测定精四氯化钛中铁含量,以柠檬酸为样品处理剂,添加草硫混酸消除磷砷等元素的干扰,通过标准加入法采用空气-C2H2火焰原子吸收光谱法进行测试。测试条件为:灯电流8 mA,燃烧器高度12 mm,狭缝宽0.1 nm,乙炔流量3.2 L/min。研究结果表明:该方法加标回收率为98%~102%,相对标准偏差小于2%。该方法简便、快速、准确。     

火焰原子吸收光谱法测定特殊硅铁中微量钙

采用氢氟酸、硝酸分解试样,加氯化铵络合钙,六次甲基四胺沉淀干扰杂质,控制体系的酸度为中性,加三乙醇胺作增感剂,镧盐作释放剂,以火焰原子吸收光谱法对特殊硅铁中微量钙进行测定,方法的相对标准偏差为1.72%~5.63%,回收率为92.00%~105.00%。     

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。