HPLC法测定3-氨基-4-氯苯甲酸的含量

建立用HPLC法测定 3-氨基 - 4 -氯苯甲酸的含量 ,采用KromasilC18柱 ,以甲醇 - 0 .0 5 % (φ)磷酸水溶液 (体积比 6 5 :35 )为流动相 ,流速 1.2mL·min-1,线性范围 0 .0 8～ 0 .4 0× 10 -4g·L-1,相关系数r=0 .9999,加标回收率为 10 1% ,RSD为 0 .98% (n =6 )。该法操作简便、准确。     

超高效液相色谱-串联质谱法测定无糖食品中木糖的含量

以自制的13C-木糖为内标,建立了无糖食品中木糖的高效液相色谱-串联四级杆质谱联用测定法。以Phenomenex Lichrosorb 5色谱柱(250mm×4.6mm,5μm)为分离柱,乙腈-水(V/V=80∶20)为流动相,以水提取样品,在电喷雾正离子选择反应检测模式下进行定性定量分析。该方法的检出限为10ng/mL,线性范围为10～1000ng/mL,加标回收率为96.09%～99.90%,相对平均偏差(n=5)为1.2%～2.5%。     

毒·唑磷乳油的气相色谱分析

采用 5 %OV -10 1/GasChromQ(15 0～ 180 μm)色谱柱 ,邻苯二甲酸二戊酯为内标物 ,对毒·唑磷乳油有效成分毒死蜱、三唑磷含量进行气相色谱分析 ,毒死蜱、三唑磷变异系数分别为 1.6 3 %和 0 .6 7% ,线性相关系数分别为 0 .990 7和 1.0 0 6 9;回收率分别为 99.1%～ 10 0 .1%和 99.6 %～ 99.7%。     

高效液相色谱快速测定茶叶中儿茶素的含量

分析了酸的种类及 pH对高效液相色谱 (HPLC)法测定表儿茶素 (EC)、表没食子儿茶素没食子酸酯(EGCG)、表儿茶素没食子酸酯 (ECG)、表没食子儿茶素 (EGC)、儿茶素 (C)和咖啡因的影响 ,实验表明 :酸尤其是乙酸不仅能改善各组分的峰形 ,而且对保留时间和出峰顺序均有较大的影响。确定了简单、快速分析 5种儿茶素及咖啡因的高效液相色谱分析方法。采用C18反相柱 ,水 -甲醇 -乙酸 ( 73. 0 / 2 3. 0 / 2 . 0 )为流动相 ,在流速为 1. 0mL·min-1,柱温 30℃ ,检测波长 2 80nm时等度洗脱分析样品 ,分析时间仅为 2 5min ,线性范围为 0 . 8～ 90mg·mL-1(r =0 998～ 0 999) ,回收率为 98. 2 %～ 10 0 . 3%,检测限为 5～ 10ng。     

高效液相色谱法分析甲基丙烯酰氧乙基三甲基氯化铵中的阻聚剂

利用反相高效液相色谱法 (HPLC) ,采用ExtendC18柱、以甲醇 -水 ( 0 .0 5 %高氯酸 )为流动相 (体积比为 5 5 :45 ) ,二极管阵列检测器对甲基丙烯酰氧乙基三甲基氯化铵 (简称DMC)中的阻聚剂对羟基苯甲醚进行了检测。试验结果证明 ,对羟基苯甲醚在0 .0 2mg/mL～ 2mg/mL浓度范围内与峰面积呈良好的线性关系。方法回收率为 98.9%～ 10 1.6% ,相对标准偏差为 1.3 2 % ,最低检测限为 5× 10 - 4mg/mL。     

高效液相色谱法测定20%高效氯氰菊酯·胺菊酯乳油中氯氰菊酯和胺菊酯的含量

采用高效液相色谱法 ,使用正相色谱柱 (ZORBAXRX SIL)和紫外检测器 ( 2 40nm)同时测定高效氯氰菊酯和胺菊酯。流动相为正己烷 +乙酸乙酯 ( 93+7) ,该方法的标准偏差为 0 .0 7%和 0 .0 9% ,变异系数为0 .69%和 0 .9% ,回收率为 99.1%～ 10 1.3%和 99.7%～ 10 1.2 %。     

液相色谱-串联质谱测定豆芽中4种四环素类药物残留量研究

建立了液相色谱-串联质谱法测定豆芽中金霉素、土霉素、四环素和强力霉素4种四环素类抗生素残留量的方法。样品用0. 1 mol/L EDTA-Mellvaine缓冲液超声提取,HLB柱净化,C_(18)色谱柱分离,正模式下检测。4种四环素类抗生素在5～200μg/L范围内线性关系良好;方法定量限(S/N=10)为1. 5～6. 0μg/kg;添加水平为5、10、20μg/kg时,平均回收率在70. 2%～93. 3%之间;相对标准偏差(RSD,n=6)为8. 5%～13. 7%。方法简单快速,灵敏度高,成功应用于市场上绿豆芽和黄豆芽的检测。     

微乳色谱法同时测定化妆水中9种防腐剂

建立同时测定化妆水中9种防腐剂的微乳色谱方法。化妆水样品经甲醇溶解、超声提取后,经0. 22μm微孔滤膜过滤,色谱柱为Diamonsil C18柱(250 mm×4. 6 mm,5μm),以3. 0%(W/V)十二烷基硫酸钠(SDS)-6. 0%(V/V)正丁醇-0. 4%(V/V)正辛烷-90. 6%(V/V) 0. 1%磷酸水为流动相,柱温为30℃,检测波长254 nm,流速0. 7 m L/min,标准曲线法定量。9种防腐剂在19 min内彼此完全分离,在0. 945～4999. 2μg/m L的范围内线性关系良好,相关系数r0. 9996,平均回收率为95. 1%～104. 6%,RSD为0. 57%～3. 30%。该方法绿色环保、简单灵敏、准确快速,可用于化妆水中多种防腐剂的同时测定。     

HILIC-MS/MS测定牛奶中4种含氮化合物的含量

建立同时检测三聚氰胺、三聚氰酸、尿酸、二氰二胺含量的高效液相-质谱联用方法。采用亲水色谱-串联质谱方法,色谱柱为Agilent Hilic柱(4. 6 mm×100 mm,3. 5μm),以乙腈-水(1∶1)为流动相进行恒度洗脱,流速为1 m L/min,进样量10μL,柱温为25℃。结果三聚氰胺在浓度范围0. 5～20 ng/m L、三聚氰酸、二氰二胺、尿酸的浓度范围均在100～4000 ng/m L内线性关系良好(R≤0. 9986),加样回收率均在82. 5%～115. 0%之间。本方法简便、快速、灵敏度高,适于同时测定牛奶中三聚氰胺、二氰二胺、三聚氰酸、尿酸的含量。     

多种菊酯类农药在茶叶中的残留量分析方法研究

采用SPBTM- 6 0 8(30m× 0 .2 5mm× 0 .2 5 μm)毛细管柱为分离柱 ,ECD检测 ,测定了茶叶中甲氰菊酯、功夫菊酯、氟氯氰菊酯、氯菊酯、氯氰菊酯、氰戊菊酯和溴氰菊酯等的残留。本方法对 7种农药的回收率范围为 85 .90 %～ 92 .5 3% ,变异系数为 1.10 %～ 7.0 5 % ,最小检出量为 0 .4～ 1.0×10 - 1 1 g。     

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.     

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.