微波消解离子色谱法测定锂云母中铷、铯

建立了微波消解离子色谱法测定锂云母中铷、铯含量的方法。通过实验确定了样品处理条件、淋洗液浓度和淋洗液流速。方法对铷和铯的检出限分别为0.012 mg/L和0.013 mg/L,线性相关系数r大于0.999 9。对实际锂云母样品进行重复6次测定,并做了加标回收实验,相对标准偏差RSD为0.38%,加标回收率为97.39%~102.8%。经国家标准品验证,测定值与标准值相符。该方法快速准确,能达到测定锂云母中铷、铯含量的分析要求。     

火焰原子吸收光谱法测定浆粕中的铁元素

建立火焰原子吸收光谱法测定浆粕中铁元素含量的方法,在选定的仪器工作条件下,采用标准加入法考察了方法的准确度和精密度。结果表明,该方法检出限为0.022μg/m L,加标回收率为97.2%,相对标准偏差(RSD)为1.28%。此方法简单易操作、快速可靠,可用于浆粕中铁含量的测定。     

火焰原子吸收光谱法测定浆粕中的铁元素

建立火焰原子吸收光谱法测定浆粕中铁元素含量的方法,在选定的仪器工作条件下,采用标准加入法考察了方法的准确度和精密度。结果表明,该方法检出限为0.022μg/m L,加标回收率为97.2%,相对标准偏差(RSD)为1.28%。此方法简单易操作、快速可靠,可用于浆粕中铁含量的测定。     

碱熔-超声浸提在土壤氟化物测量中的应用

针对地质调查化学分析中批量测定土壤中全态氟化物不易前处理的特点,采用碱熔-超声浸提的前处理手段,并通过离子选择电极法测量,建立了一种测定土壤中全态氟化物含量的分析方法,并对该方法原理做出阐释。方法检出限低至18μg/g,相对标准偏差小于2.1%,相对误差小于2.7%。该方法简单快捷、准确度高、精密度好,适用于土壤中全态氟化物含量的批量处理与测定。     

活性炭富集-电感耦合等离子体发射光谱法测定精矿中金的含量

实验详细考察研究了活性炭富集-电感耦合等离子体发射光谱测定金精矿中金的含量。实验主要研究了称样量、焙烧方式、盐酸浓度对活性炭吸附的影响及电感耦合等离子体发射光谱谱线的选择。该方法测量的范围为1.00～200μg·g^-1,检出限为0.037μg·g^-1,测定的结果的相对标准偏差为0.93%～2.50%,测定的结果的相对误差为0.32%～0.72%,加入标准物质的回收率为94.40%～105.20%。本方法与国家标准测定结果吻合良好。具有精密度好,准确度高,结果令人满意,能够满足生产需求。     

退镀铜溶液中铜的测定

采用原子吸收分光光谱法建立了测定退镀铜溶液中铜的分析方法。分析了共存物质和高氯酸对铜测定的影响,进行了精密度分析及样品合成等试验。结果表明,共存物质硫酸对测定无影响,铬酸酐质量浓度超过40 g/L对测定有负干扰,加入高氯酸可消除影响。高氯酸可加热冒烟消除。该方法的相对偏差小于1.00%(n=5),此分析方法的精密度好、准确度高。     

内标法测定镍钒合金中的钒含量

一种镍钒合金中钒含量的测定方法。本方法采用王水溶解镍钒合金,使用纯钒为标准物质,使用钇为内标元素,向标准溶液和待测样品溶液中加入等量的内标元素钇,再使用电感耦合等离子体发射光谱仪内标法测试样品中的钒含量,该方法能有效的补偿因仪器波动及操作差异而导致的数据偏差,该方法能较准确的测试镍钒合金中钒含量较高的样品。     

离子色谱法测定镍锰酸锂正极材料中的硫酸根含量

采用离子色谱法测定镍锰酸锂中硫酸根离子的含量，用盐酸和双氧水溶解试样，通过固相萃取柱净化后至离子色谱仪上进样测试，通过多次对比实验优化了试验方法。在优化的试验条件下，硫酸根在0～20.0μg/L范围内具有良好的线性关系，线性相关系数为0.999 8。对4个不同含量的样品分别进行了11次平行测定，相对标准偏差(RSD)为1.6%～5.9%。在镍锰酸锂试样中加入硫酸根标液进行加标回收实验，硫酸根离子的加标回收率在96.1%～106.3%。与传统的硫酸钡比浊法相比，离子色谱法操作简便快捷，方法检出限低，测量范围更宽，干扰少，测定结果可靠，再现性良好，适合大批量快速样品分析。     

六氟磷酸锂、氟化锂中微量硫酸根的ICP方法研究

目前硫酸根含量的检测采用比浊法和离子色谱法,硫酸钡比浊法检出限高、稳定性差、准确度低、工作效率低;离子色谱法效率低、成本高,很难满足六氟磷酸锂工业生产的快速发展。本文建立了一种能够高效、准确地测定六氟磷酸锂和氟化锂中硫酸根的方法。通过ICP-OES电感耦合等离子体光谱仪检测硫元素含量,计算六氟磷酸锂、氟化锂中硫酸根的含量。结果表明,该方法具有检出限低、稳定性好、准确度高、工作效率高等优势。     

火焰原子吸收光谱法测定水中的镍

采用疏基棉分离富集技术,以火焰原子吸收光谱法测定了水中痕量镍元素的含量,相对标准偏差为2.3~2.5,回收率为99.8%~100.1%,取得了比较满意的实验结果。该方法简单、快速并具有良好的精密度和准确度。重点讨论了前处理方法、共存离子对测定结果的影响。     

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.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.