碧冬茄的挥发性化学成份鉴定及其驱蚊活性研究初报

碧冬茄的挥发性化学成份鉴定及其驱蚊活性研究初报么恩云，李正名，平霄飞，施红林，毕富春，王文丽（元素有机化学国家重点实验室，南开大学元素有机化学研究所天津３０００７１）杨瑞华（南开大学生物系天津３０００７１）在天然植物中蕴藏着极其丰富的生理活性物质。近...     

气相色谱-串联质谱法测定植物源驱蚊产品中82种风险性化学物质

为同时筛查植物源驱蚊产品中致敏性芳香剂和农药化合物,建立了一种基于溶剂提取/气相色谱-串联质谱（GC-MS/MS）同时检测78种致敏性芳香剂和4种农药化合物的方法。采用极性色谱柱Agilent VF-WAXms进行色谱分离,通过不同的特征离子对对部分共流出化合物进行定性定量分析。以阳性样品为研究对象对提取溶剂和提取时间进行优化,确定最佳提取条件为：以二氯甲烷为提取溶剂,在30℃恒温条件下超声提取30 min。结果表明,82种目标化合物在对应质量浓度范围内具有良好的线性关系,相关系数（r）均大于0.992 0,定量下限为0.02～5.0 mg/kg,回收率为60.0%～120%,相对标准偏差（RSD）不大于9.5%。将该方法用于驱蚊贴、驱蚊扣、驱蚊液和驱蚊凝胶等29个样品的筛查,共检出33种致敏性芳香剂和1种农药（驱蚊酯）。80%以上的样品中检出α-蒎烯、β-蒎烯和D-柠檬烯等11种致敏性芳香剂,最高含量为116～21 140 mg/kg;3个驱蚊液中检出驱蚊酯,含量为10 200～21 350 mg/kg。该方法操作简单、结果准确,可用于驱蚊产品中致敏性芳香剂和农药化合物的同时筛查和含...     

新型驱蚊产品中35种挥发性致敏芳香剂的筛查方法及挥发规律研究

基于顶空/气相色谱-串联质谱（HS/GC-MS/MS）建立了驱蚊贴、驱蚊扣、驱蚊手环等新型驱蚊产品中35种挥发性致敏芳香剂的分析方法。35种物质经中等极性色谱柱Agilent DB-17MS分离,采用电子轰击源（EI源）通过多反应监测（MRM）模式进行检测。考察了37个新型驱蚊样品在顶空温度分别为40℃和100℃时的筛查结果,40℃顶空条件下筛查出α-蒎烯、β-蒎烯和D-柠檬烯等14种致敏芳香剂,此外,100℃时还检出香叶醇、香芹酮等其它12种致敏芳香剂。以儿童用驱蚊贴和驱蚊扣为例,比较了不同顶空温度对各目标化合物响应强度的影响,结果表明,40℃时α-蒎烯、β-蒎烯和D-柠檬烯等8种致敏芳香剂的响应强度小于100℃时。对37个样品在40℃平衡温度下的半定量分析表明,α-蒎烯、β-蒎烯、D-柠檬烯等9种致敏芳香剂的检出率最高,其中α-蒎烯和D-柠檬烯的最高响应强度大于106。选择驱蚊贴和驱蚊扣进一步考察了α-蒎烯、β-蒎烯、D-柠檬烯、薄荷醇和樟脑5种致敏芳香剂在40℃下放置不同时间的挥发规律,发现α-蒎烯、β-蒎烯和D-柠檬烯放置12 h的响应强度为初始的20%～21%,薄荷醇和樟脑放...     

实时直接分析质谱法快速鉴别天然驱蚊产品中的人工添加剂

采用DART-MS(实时直接分析质谱法)建立了一种简单快速测定人工合成驱蚊化合物如DEET(避蚊胺)、BAAPE(驱蚊酯)等的方法.在常温常压下,无需对天然驱蚊产品进行任何预处理,通过比对标准品的质谱信号离子,即可快速鉴别出天然驱蚊产品中的人工添加剂.该方法大大缩短了分析时间,并且具有原位、准确且高通量的优点.     

气相色谱法快速测定儿童驱蚊扣中菊酯类物质

建立快速测定儿童驱蚊扣中菊酯类残留的气相色谱法。以甲醇为萃取溶剂,萃取液经中性氧化铝固相萃取小柱净化,以乙酸乙酯为洗脱溶剂,洗脱液经旋转蒸发浓缩后,用电子捕获检测器检测,外标法定量。8种菊酯类化合物的质量浓度在0.05~1.00 mg/L范围内与色谱峰面积成良好的线性关系,相关系数均大于0.998,检出限为0.48~2.90μg/L。3个加标水平样品的平均回收率为93.8%~119.7%,测定结果的相对标准偏差为0.88%~6.43%(n=5)。该方法样品前处理简便,准确度和精密度良好,可用于驱蚊扣产品中菊酯类物质的检测。     

气相色谱法同时测定驱蚊护肤品中的13种昆虫驱避剂

<正>驱避剂是一种能使昆虫无法识别和发现其叮咬目标,从而远离潜在目标的物质。驱避剂可用在皮肤和衣服上等,令使用者免遭蚊、虱、蜂和蚤类等害虫的叮咬。驱避剂原药一般不能直接应用,必须经过一定的加工过程转变成不同的使用形态,如驱蚊膏、驱蚊乳、驱蚊花露水等~([1-5])。如果驱蚊护肤品中     

气相色谱-质谱法测定驱蚊用品中避蚊胺的含量

<正>蚊虫是夏季主要卫生害虫,被蚊虫叮咬会引起皮肤红肿、瘙痒等症状,且可能被传染多种疾病,严重危害人类健康~([1-3])。而避蚊胺(DEET),又称N,N-二乙基-3-甲基苯甲酰胺,是一种广谱、高效、环保的人工合成昆虫驱避剂。DEET对苍蝇、虱子、蚂蚁、蚊子、蟑螂、蠓虫、白蛉、蝉等均有良好的驱避效果,是市售驱蚊用品(驱蚊花露水、驱蚊手环、驱蚊贴等)中广泛添加的主要驱蚊成分。但有研究表明,     

驱蚊原理的化学解读

介绍了蚊子的嗅觉系统、气味分子与气味结合蛋白和嗅觉受体蛋白作用的原理,并扼要介绍常用驱避剂DEET驱蚊原理的一种假说以及蚊虫驱避剂的发展前景。     

毛细管电泳结合高效液相色谱-质谱用于天然产物活性成分的筛选

发展了毛细管电泳(CE)和高效液相色谱-质谱(HPLC-MS)相结合的用于天然产物中活性成分筛选和鉴定的方法。该方法中,用HPLC半制备柱对天然产物粗提物进行分离纯化,再用CE对HPLC纯化后的组分进行活性测试。根据HPLC-MS/MS提供的二级质谱数据,即可确定活性成分的化学结构。以乙酰胆碱酯酶为实验模型,对我们发展的筛选方法进行了验证。从黄连粗提物中确定了药根碱、巴马汀等7种活性成分,并通过CE测定了它们的半抑制率(IC₅₀)值。与传统的天然产物分离纯化和活性筛选方法相比,该方法具有简单、微量、快速、准确的优点。本文建立的方法为天然产物粗提物中活性成分的筛选提供了新技术。     

气相色谱法测定驱蚊功效印刷品中3种功效化合物

建立了气相色谱–氢火焰离子技术测定功效印刷品中3种驱蚊成分的方法。样品用二氯甲烷进行超声提取,邻苯二甲酸二丁酯为内标,利用毛细管色谱柱HP–5(30 m×0.32 mm,0.25μm)分离,保留时间定性,内标法定量。结果表明,3种驱蚊功效物质色谱分离良好,在质量浓度0.1~1.0 mg/L范围内与色谱峰面积呈线性相关。方法定量限(10S/N)为1.25 mg/kg,样品加标回收率为97%~108%,测定结果的相对标准偏差不大于8.1%(n=6)。该方法快速、可靠、准确、简便,适用于驱蚊功效的印刷品中3种驱蚊功效类化合物的分析检测。     

Modeling of lithium-ion batteries is becoming viral: where to go?

Journal of Solid State Electrochemistry - We briefly summarize the most popular theoretical/computational techniques being used to model lithium-ion batteries and suggest some future...     

On the estimation of the strength of supramolecular complexes of fullerenes

The accurate estimation of the free energy changes in solution for supramolecular complexes is one of the most important challenges for quantum chemistry in this century. In general, there is a good correlation between the association constants determined experimentally and the gas phase binding energies calculated using the most popular density functional methods. However, when the receptors adopt very different structures in the gas and condensed phase, this approach does not work, leading to unreliable predictions. We discuss this problem in detail using three popular fullerene receptors: Aida's dimeric porphyrins, buckycatchers I, and II. We found that it is possible to obtain a reliable order of affinities using gas phase binding energies when a special attention is put on analyzing the structure adopted by the receptor in the gas and condensed phases.     

Identification of Active Sites and Structural Characterization of Reactive Ionic Intermediates by Cryogenic Ion Trap Vibrational Spectroscopy

Cryogenic ion trap vibrational spectroscopy paired with quantum chemistry currently represents the most generally applicable approach for the structural investigation of gaseous cluster ions that are not amenable to direct absorption spectroscopy. Here, we give an overview of the most popular variants of infrared action spectroscopy and describe the advantages of using cryogenic ion traps in combination with messenger tagging and vibrational predissociation spectroscopy. We then highlight a few recent studies that apply this technique to identify highly reactive ionic intermediates and to characterize their reactive sites. We conclude by commenting on future challenges and potential developments in the field.     

Removal of the impurities from environmental water samples for tritium measurement by liquid scintillation counting

Liquid scintillation counting is the most popular method for tritium measurement, however, it takes much time and a lot of doing to distill off the impurities before mixing the sample water and liquid scintillation cocktail. We have investigated the possibility of an alternative method to the distillation. We have found out that the filtration can be an alternative to distillation for the environmental water samples before electrolytic enrichment.     

Analysis of tea components by high-performance liquid chromatography and high-performance capillary electrophoresis

Tea is one of the most popular beverages in the world. The number of reports on the analysis of tea components, especially for catechins, has recently been increasing. We review the recent reports on the analysis of tea components using the analytical methods of high-performance liquid chromatography and high-performance capillary electrophoresis.     

On application of directons to functional classification of genes in prokaryotes

Functional classification of genes represents one of the most basic problems in genome analysis and annotation. Our analysis of some of the popular methods for functional classification of genes shows that these methods are not always consistent with each other and may not be specific enough for high-resolution gene functional annotations. We have developed a method to integrate genomic neighborhood information of genes with their sequence similarity information for the functional classification of prokaryotic genes. The application of our method to 93 proteobacterial genomes has shown that (i) the genomic neighborhoods are much more conserved across prokaryotic genomes than expected by chance, and such conservation can be utilized to improve functional classification of genes; (ii) while our method is consistent with the existing popular schemes as much as they are among themselves, it does provide functional classification at higher resolution and hence allows functional assignments of (new) genes at a more specific level; and (iii) our method is fairly stable when being applied to different genomes.     

纤维素衍生物手性固定相用于高效液相色谱对映体分离

纤维素衍生物是目前高效液相色谱 (HPLC)中应用最为广泛的手性固定相之一 ,对各种类型的外消旋体都表现出了很高的对映体选择性 ,因其负载量大特别适用于对映体制备分离。本文对纤维素衍生物手性固定相的种类、影响手性选择性的因素以及手性识别的机理进行了较为全面的评述 ,并展望了研究前景     

如何评估：中国现当代通俗文学批评标准的建构和价值评析

文学的批评标准需要具有适应性。用新文学（或精英文学）的批评标准批评中国现当代通俗文学显然不合适,“道”不同,沿途的“风景”也不一样。评估中国现当代通俗文学的价值及优劣,首先要明确“通俗性”的批评标准和思维路径,这是构建中国现当代通俗文学批评标准的“入口”。传统、文化、市场是中国现当代通俗文学价值评估的“三标准”,显示的是中国现当代通俗文学的特性。从正确的“入口”进去,确立科学的批评标准,我们就能明确中国现当代通俗文学在现代中国具有独特的贡献,对中国现当代通俗文学的价值和缺陷才能进行清晰的剖析和科学的评估。在此基础上建立的通俗文学的批评标准才有科学性和有效性。     

Heteroatom-substituted rhodamine dyes: Structure and spectroscopic properties

Rhodamine is one class of most popular dyes used in fluorescence imaging due to the outstanding photoproperties including high brightness and photostability. In recent years, replacement the xanthene oxygen with other elements, especially silicon, has attracted great attentions in the development of new rhodamine derivatives. This review summarized the structures and photophysical properties of heteroatom-substituted rhodamines. We hope this review can help to understand the structure-property relationships of rhodamine dyes and then elucidate the way to create derivatives with improved photoproperties.