盐析法提取聚季铵盐-7中残余丙烯酰胺的研究

采用硫酸钠将聚季铵盐-7高聚物析出,然后用甲醇／异丙醇对其中的残留单体丙烯酰胺（AM）进行提取,同时用高效液相色谱对提取液中的丙烯酰胺进行测定,得到了最佳提取方案：V（甲醇）：V（异丙醇）：1：1,搅拌提取时间60min;最佳色谱条件为：流动相V（甲醇）：V（水）=4：96,流速1．0mL／min;在最佳条件下测试回收率在97．37％～99．68％范围内,相对标准偏差为2．96％。     

高效液相色谱法测定化妆品中的苯氧异丙醇

以超声辅助提取法对不同基质类型的化妆品样品进行预处理,采用高效液相色谱法测定化妆品中的苯氧异丙醇,色谱条件为:Kromasil C18色谱柱(250 mm×4.6 mm i.d.,5μm),流动相为V(水)∶V(乙腈)∶V(甲醇)∶V(四氢呋喃)=60∶25∶10∶5的混合溶液,流速1.2 mL/min,检测波长268 nm,柱温30℃。结果表明,在此条件下苯氧异丙醇在1.0~200.0μg/mL范围内与相应的峰面积具有良好的线性关系(相关系数r=0.999 9),线性回归方程为A=74 280ρ-23 780,回收率为95.6%~102.4%,RSD为0.66%~1.05%。     

杜仲籽粕中桃叶珊瑚甙的制备

用微波法进行杜仲籽粕中桃叶珊瑚甙的提取,通过溶剂萃取结合柱色谱分离纯化得到桃叶珊瑚甙纯品。确定适宜的微波提取条件为:φ(乙醇)=30%的水溶液为提取剂,微波功率560 W,按m(提取剂)/m(原料)=28提取1次,10 s,桃叶珊瑚甙的提取率达到95.55%;而超声波提取需90 min,提取率为90.69%;索氏回流法则需6 h,提取率仅为88.03%。粗提物用V(乙酸乙酯)∶V(提取液)=3∶1萃取2次,V(正丁醇)∶V(水相)=2∶1萃取3次后浓缩得浸膏;然后以V(甲醇)∶V(水)∶V(冰乙酸)=24.5∶75∶0.5为流动相,进行反相制备色谱分离,最后得到质量分数为92.32%的桃叶珊瑚甙产品,用核磁共振及质谱进行了确认。该研究工作的新颖性,已为教育部中南大学科技查新工作站2006年3月16日出具的第200643Z1100004号《科技查新报告》所证实。     

从L-阿拉伯胶提取L-阿拉伯糖

阿拉伯胶在硫酸作用下水解得到含L 阿拉伯糖的混合液,经w(C2H5OH)=90%的乙醇萃取,再经工业乙酸沉淀,可得粗L 阿拉伯糖。正交实验确定了酸性水解反应的影响因素和最佳条件为:水解温度90～100℃,w(H2SO4)=1 0%,L 阿拉伯糖的粗收率为85%,质量分数为66 7%。经双柱色谱分离提纯L 阿拉伯糖,所用洗脱剂分别为:V(正丁醇)∶V(乙酸乙酯)∶V(异丙醇)∶V(乙酸)∶V(水)=3 5∶10∶6 5∶3∶3和V(乙酸乙酯)∶V(异丙醇)∶V(水)=5∶2 2∶1 1,得到收率大于50%,质量分数为99%的L 阿拉伯糖。     

高效液相色谱法测定化妆品中熊果酸的含量

采用甲醇超声提取,液相色谱分离的方法测定化妆品中熊果酸的含量。色谱条件为:Agilent HC-C18(250 mm×4.6 mm,5μm)色谱柱,流动相V(甲醇)∶V(水)∶V(冰乙酸)=87∶13∶0.03,流速1.0 mL/min,紫外检测波长215 nm。结果表明,在此条件下熊果酸在0.2μg/mL~103μg/mL与相应的峰面积具有良好的线性关系(r>0.999 7),线性回归方程为y=25.367 5x 0.546 9,回收率在96.4%~101.3%,方法精密度RSD<3.6%。     

超临界萃取-HPLC法检测烟叶中马来酰肼残留

用超临界CO2萃取烟叶中农残马来酰肼,用高效液相色谱检测马来酰肼残留量。通过单因素和正交实验对萃取过程中夹带剂、萃取压力、萃取温度、萃取时间和CO2流量进行了考察,确定了最佳萃取工艺条件为:夹带剂V(甲醇)∶V(异丙醇)=1∶1,萃取压力20 MPa,萃取温度55℃,萃取时间100 min,CO2流量23 g/min。在该条件下,采用高效液相色谱检测烟叶中马来酰肼残留量,分析的重现性和稳定性最佳。结果表明,马来酰肼回收率为94.08%~97.86%,RSD均小于6%,检出限为2.7μg/g。     

高效液相色谱法同时测定化妆品中15种防晒剂

优化和改进了《化妆品卫生规范》(2007年版)规定的测定化妆品中15种防晒剂的高效液相色谱法。样品经V(甲醇)∶V(四氢呋喃)∶V(水)∶V(0.067%高氯酸)=250∶450∶300∶0.2的混合溶液提取后,使用Kromasil C18色谱柱分离,以甲醇、四氢呋喃和0.067%高氯酸的混合溶液为流动相进行梯度洗脱,流速1 m L/min,检测波长311 nm。结果表明:在给定的质量浓度范围内15种防晒剂的峰面积与质量浓度呈良好的线性关系,方法回收率为85.6%~115.9%,检出限为0.8~12.5 ng。     

水溶性超高分子量聚丙烯酰胺/丙烯酸的研制及竞聚

以丙烯酰胺(AM)和丙烯酸(AA)为原料,采用水溶液自由基共聚法制备超高分子量聚丙烯酰胺/丙烯酸(PAM/AA)共聚物。由正交实验研究了单体浓度、引发剂用量、助剂尿素用量、单体配比、反应温度对聚合物相对分子质量的影响。结果表明,最佳条件为:m(AM)∶m(H2O)=30%,m(AM)∶m(AA)=3,m(I)∶m(AM)=0.3%,m(尿素)∶m(AM)=0.3%,温度20℃,在此条件下,产物分子量高达5 120万,AM和AA的竞聚率为r AM=0.684、r AA=0.278,其中单体残余量由紫外分光光度法测得。     

光盘级聚碳酸酯醇解制双酚A

为实现对光盘级聚碳酸酯的降解利用,以甲苯为溶剂、NaOH为催化剂、Na2S为产品保护剂,常压下对其进行甲醇醇解反应制备双酚A,同时考察了各个反应因素对醇解反应的影响。研究结果表明:光盘级聚碳酸酯可在40 min反应时间、60℃反应温度、V(甲醇)∶V(甲苯)=1∶3、m(PC/g)∶V(有机溶液/mL)=1∶3.15、m(Na2S)∶m(PC)=1∶30、m(NaOH)∶m(PC)=1∶20及匀速搅拌的最佳反应条件下实现完全醇解解聚,双酚A收率达到88%以上。     

反相高效液相色谱法测定化妆品中的神经酰胺

采用反相高效液相色谱法测定化妆品中的神经酰胺。色谱条件为:SHIMADZU Shim-pack VP-C18ODS(150 mm×4.6 mm,5μm)色谱柱,C18ODS保护柱芯,流动相V(甲醇)∶V(异丙醇)=55∶45,流速1.0 mL·min-1,柱温30℃,紫外检测器检测,波长205 nm,检测池温度40℃。结果表明,在此色谱条件下,神经酰胺在0~5 g·L-1与相应的峰面积具有良好的线性关系(r=0.991 4),线性回归方程为A=1 466 341ρ,回收率在96.5%~101.2%。     

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.