紫外-可见分光光度法测定噻唑磷含量

建立紫外-可见分光光度法测定噻唑磷含量的方法.溶剂为正己烷,测定波长为213.9 nm,样品质量浓度为36.375 mg/L.采用对照比较法计算含量.噻唑磷在23.92～95.68 mg/L质量浓度范围内呈线性关系线性相关系数为0.9996.精密度实验RSD不超过0.74%,准确性分析表明噻唑磷的回收率在100.21%～101.16%之间.     

气相色谱法测定噻唑磷的含量

建立了气相色谱法测定噻唑磷含量的方法,色谱柱为HP-5,FPD检测器,进样口和汽化室温度250℃,程序升温,不分流进样.对照品的进样量在5.98～53.82 mg/L时,峰面积与进样量呈良好的线性关系,线性相关系数为0.9997,噻唑磷的回收率在97.85%～101.85%之间,相对标准偏差为2.19%.     

比浊法测定含铜基体样品中的微量氯

本文研究了比浊法测定含铜基体样品中微量cl一的快速分析方法.方法液体最低检出浓度为0.2mg·L-1,固体最低检出浓度为5μg·g-1.测定含Cl-为0.0014%,0.0058%,0.0070%的CuSO4,CuCO3·Cu(OH)2和CuO样品,相对标准偏差分别为4.5%,3.2%,2.4%;加标回收率分别为98.2%～105.1%,98.8%～107.6%,96.4%～105.5%.     

气相色谱测定土壤中霜霉威的残留

应用气相色谱氮磷检测器对土壤中霜霉威的残留量进行了测定,方法的最低检出量为1 × 10-10g,最低检出质量分数为0.03 mg/kg,在0.051、0.51、1.02 mg/kg添加水平下,添加回收率范围为91.21%～99.96%,变异系数范围为2.24%～5.39%.     

菠菜中噻虫嗪的残留检测与消解动态

采用高效液相色谱分析技术测定了噻虫嗪在菠菜中的残留动态和最终残留.噻虫嗪的最低检出量为1 ng,最低检出质量分数为0.002 mg/kg.在菠菜中的平均回收率为90.5%～101.4%,相对标准偏差0.75%～1.21%.噻虫嗪在土壤和菠菜中的半衰期分别为2.3 d.按180 g/hm2剂量施药3 d后,菠菜中最高残留量为0.55 mg/kg.     

氟啶脲在冬枣中的残留检测及消解动态

采用高效液相色谱法测定了氟啶脲在冬枣中的残留动态.氟啶脲的最低检出量为4.45 ng,最低检出质量分数为0.04 mg/kg.在冬枣中的平均回收率为71.3%～91.7%,相对标准偏差为0.95%～5.23%,符合农药残留分析的要求.实验结果表明:氟啶脲在冬枣中的半衰期为3.1 d,原始沉积量为0.95 mg/kg.按0.05 g/kg药液质量浓度施药7 d后,冬枣中最高残留量为1.37 mg/kg.     

氟草烟在稻田水及土壤中残留分析方法

通过衍生化反应和气相色谱检测来测定稻田水、土壤样品中氟草烟的残留.氟草烟的最小检出量为2.0×10-12g,最低检出质量分数稻田水中为0.001 mg/kg、土壤中为0.002 mg/L.稻田水中氟草烟的平均添加回收率为96.16%～103.20%,变异系数为2.34%～6.97%;土壤中的平均添加回收率为81.35%～94.27%,变异系数为4.26%～6.52%.     

高效液相色谱法同时测定甘蔗及土壤中莠灭净与敌草隆的残留

建立了用高效液相色谱法同时测定甘蔗及土壤中莠灭净与敌草隆的残留分析方法.样品经甲醇提取,二氯甲烷萃取和中性氧化铝柱层析净化,HPLC法测定,方法最小检出量莠灭净为1.2×10-9g,敌草隆为1.5×10-9g.莠灭净在土壤和甘蔗中的最低检出质量分数分别为0.015、0.02 mg/kg,方法添加回收率分别为82.12%～90.97%、85.89%～92.26%,相对标准偏差分别为1.70%～5.73%、0.40%～5.78%;敌草隆在土壤和甘蔗中的最低检出质量分数分别为0.01、0.02 mg/kg,方法添加回收率分别为80.93%～82.19%、81.81%～87.81%,相对标准偏差分别为2.34%～8.60%,0.35%～6.20%.     

12%噻虫嗪·噻唑磷颗粒剂的高效液相色谱分析

采用高效液相色谱法测定12%噻虫嗪·噻唑磷颗粒剂中噻虫嗪和噻唑磷的质量分数,使用C18反相柱和紫外可变波长检测器,以乙腈+0.3%冰乙酸水溶液为流动相,用外标法对有效成分进行分析和定量。结果表明,噻虫嗪和噻唑磷的线性相关系数分别为0.999 3和0.999 4,标准偏差分别为0.056、0.140,变异系数分别为2.68%、1.35%,平均回收率分别为100.05%、99.74%。     

HPLC法测定10%噻唑磷颗粒剂含量

建立了高效液相色谱法测定10%噻唑磷颗粒剂有效成分含量的方法。采用岛津CLC-ODS(150 mm×6.0 mm,5μm)色谱柱;柱温为30℃;流动相为V(甲醇)∶V(水)=65∶35;流速为1.0 mL/min;检测波长为220 nm;噻唑磷保留时间为7.0 min。结果表明标准样品溶液进样量在0.053 5～0.855 8 mg/mL时线性关系良好(r=0.999 9、n=5),平均回收率为99.12~99.96%,RSD为0.23%。该方法专属性强,重现性好,准确度高,可用于10%噻唑磷颗粒剂有效成分的含量测定。     

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.     

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.