马拉硫磷对映体色谱拆分方法的建立

建立了马拉硫磷对映体的高效液相色谱正相体系拆分方法。分别应用了正己烷和石油醚两种流动相,在正己烷流动相体系中采用了乙醇、丙醇、异丙醇、丁醇和异丁醇有机改性剂,石油醚体系则以异丙醇为改性剂,考察,改性剂及其含量对拆分的影响。同时还考察了温度对分离的影响。实验结果显示,室温下正己烷流动相中含5％异丁醇可达最佳分离效果,分离因子为1．22。流动相中醇的含量减少使保留时间延长,分离效果增加。低温有利于对映体的分离。     

茚虫威在直链淀粉手性固定相上的对映体分离研究

茚虫威对映异构体在三[(S)-α-甲基苯基氨基甲酸]直链淀粉酯涂敷型高效液相色谱手性固定相上成功的获得了拆分.通过考察流动相中醇类改性剂种类和浓度对其对映体分离的影响,优化了色谱分离条件.结果显示:随着流动相中异丙醇和乙醇改性剂含量增加,分离度逐渐变小,当异丙醇和乙醇的含量分别为20%时,茚虫威即可达到基线分离,分离度为1.8和1.25;两种改性剂比较,乙醇比异丙醇有更高的改性效率.同时考察了分离温度对茚虫威手性分离的影响,结果表明,在15～35℃范围内,温度升高和分离度增大呈正相关关系.     

戊唑醇对映体在直链淀粉衍生物手性固定相上的拆分

利用三[(s)-α-甲基苯基氨基甲酸]直链淀粉酯涂敷型手性固定相高效液相色谱对戊唑醇对映体成功进行拆分.考察了流动相中醇改性剂种类和体积分数对手性拆分的影响.实验结果表明,当流动相中改性剂异丙醇和乙醇体积分数为2%时,戊唑醇获得最大分离度3.90和5.76.同时还考察了分离温度对手性拆分的影响,结果显示分离度随温度升高呈降低趋势.     

纤维素-三(3,5-二甲基苯基氨基甲酸酯)对烯唑醇对映体的直接拆分

制备了纤维素-三(3，5-二甲基苯基氨基甲酸酯)手性固定相(CDMPC)，以正己烷为流动相，添加异丙醇为改性剂，在高效液相色谱上实现了对烯唑醇光学异构体的直接拆分，探讨了改性剂的含量及色谱柱长对拆分效果的影响，从而优化了拆分条件。试验结果显示，流动相中异丙醇含量的减少有利于对映体的拆分，但保留增强；长色谱柱也有利于对映体的分离。使用两色谱柱串连，当流动相中正己烷与异丙醇的比例为95：5时可达到最佳分离效果，分离因子为1．17。     

高效液相色谱纤维素类手性固定相对外消旋稻丰散的拆分

合成了纤维素-三(3，5-二甲基苯基氨基甲酸酯)手性固定相，制备了手性色谱柱，以正己烷为流动相，添加异丙醇为改性剂，在高效液相色谱上实现了对手性农药稻丰散光学异构体的直接拆分；系统摸索了异丙醇含量、色潜柱长度、流速及温度对拆分效果的影响，优化了拆分条件。结果显示，色谱柱长度对该化合物的拆分影响较大；流动桕巾异丙醇含量的减少以及流速减慢均有利丁对映体的拆分，但也导致保留增强；在5℃．40℃范刚内，温度升高分离度减小。使用长色谱柱，选择适温20℃，调整流动相中正己烷与异丙醇的比例为99．5：0.5(v／v)，流速为0．5ml／min时，可达到最佳分离效果，分离因子为1．38。     

氟草烟异辛酯对映体的手性拆分

利用高效液相色谱手性固定相法对氟草烟异辛酯对映异构体进行了拆分研究。使用了正己烷和石油醚两种流动相体系,正己烷流动相条件下考察了多种极性改性剂及其含量,以及温度对手性拆分的影响。实验结果显示,以异丙醇为改性剂,在正己烷体系中的分离效果最好,室温下最大分离因子可达到1．2,温度降低有利于对映体的拆分。石油醚体系的分离效果不佳。     

乙氧呋草黄对映体的手性拆分研究

进行了除草剂乙氧呋草黄对映体在自制的纤维素-三(3,5-二甲基苯基氨基甲酸酯)(CDMPC)高效液相色谱手性柱上的拆分研究。使用了两种流动相体系:正己烷-异丙醇;石油醚-异丙醇,并分别考察了流动相中加入的极性改性剂对手性拆分的影响。试验结果显示,乙氧呋草黄在两种流动相体系中都能得到最好的拆分,但正己烷体系优于石油醚体系,流动相中的极性改性剂的含量减少有利于手性拆分。在正己烷流动相条件下考察了柱长、温度对手性拆分的影响。对对映体的拆分机理进行了讨论。     

植物生长调节剂多效唑的手性分离

使用直链淀粉衍生物涂敷型手性固定相对植物生长调节剂多效唑对映异构体进行了高效液相色谱手性拆分,正己烷分别添加了乙醇、丙醇、异丙醇、丁醇和异丁醇作为流动相,考察了醇含量对拆分的影响。圆二色(CD)检测器确定了对映体的出峰顺序并测定了圆二色特性。多效唑两对映体在V正己烷∶V异丙醇=95∶5流动相条件下可以实现完全分离,分离度达1.63。230nm波长下,出峰顺序为 /-,波长超过238nm,多效唑两对映体无圆二色吸收。     

液相色谱手性拆分高效氯氟氰菊酯对映体

[方法]对映体分离是研究手性农药在环境中的选择性行为的重要前提之一,而高效液相色谱法是目前应用最为普遍的对映体分离和制备方法.对高效氯氟氰菊酯在纤维素-三-(3,5-二甲基苯基氨基甲酸酯)(Chiralcel OD-H)手性柱上的分离进行了研究,考察了流动相组成、流速以及柱温对分离效果的影响,并对高效氯氟氰菊酯对映体与固定相之间保留和分离的热力学机理进行了讨论.[结果]分别以5种体积比均为15%的醇改性上E己烷,分离因子(а)的变化顺序为异丁醇>异丙醇>正丁醇>正丙醇>乙醇;在0.4～1.1mL/min的流速范围内.分离度(Rs)随着流速的增大而逐渐减小;柱温在15～35℃范围内变化时,随着温度的升高分离闪子(а)呈降低趋势,两对映体的lnа与1/T呈良好的线性关系.手性拆分过程受焓的控制.[结论]在柱温为25℃,正己烷-异丙醇(体积比90:10)为流动相,流速1.0 mL/min时,高效氯氟氰菊酯对映体能达到基线分离,分离因子(а)和分离度(Rs)分别为1.55和4.07.     

黄烷酮对映体在自制的直链淀粉-三(3,5-二甲基苯基氨基甲酸酯)手性固定相上的直接拆分

在自制的直链淀粉-三(3,5-二甲基苯基氨基甲酸酯)手性固定相(AD-CSP)上对黄烷酮对映异构体进行了手性拆分,系统考察了流动相正己烷中,醇的含量、结构及分离温度对手性拆分的影响。实验结果表明,分离温度在20～45℃内,黄烷酮对映异构体的lnα与1/T呈良好的线性关系,手性拆分过程受焓控制;当流动相为V(正己烷)∶V(异丁醇)=90∶10、流速为0.5 mL/min、25℃时黄烷酮获最佳分离,分离度RS为1.90。     

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.     

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.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。