微分脉冲吸附溶出伏安法测定苯胺的研究

苯胺经重氮化、偶合反应定量生成的偶氮化合物具有很强的电活性。作者用微分脉冲吸附溶出伏安法测定偶氮化合物来定量分析苯胺的含量。以ＮＨ３·Ｈ２Ｏ－ＮＨ４Ｃｌ（ｐＨ＝１０）缓冲液为底液，富集电位为－０１５Ｖ，富集时间１２０ｓ，电位扫描速度４ｍＶ／ｓ，在－０６７０Ｖ处产生一个灵敏度高、峰形好的溶出峰。苯胺浓度在１０－９～１０－７ｍｏｌ／Ｌ时与峰电流成线性关系。用印染厂土壤、废水和广州垃圾填埋场的渗出液作标准回收试验，平均回收率分别为９８２％、９７０％、９７５％，测定的相对标准偏差为４３％、４０％、３３％。     

测定大气气溶胶中多环芳烃的高效液相色谱编程荧光法

建立了高效液相色谱法分析１４种多环芳烃（ＰＡＨｓ）的最佳分离条件及测定的最佳荧光激发、发射波长，多环芳烃化合物的最小检测量从０９０到５５１９ｐｇ，各化合物保留时间的相对标准偏差ＲＳＤ＜０３４％，在所测定的含量范围内具有很好的线性关系。该法用于大气气溶胶中的多环芳烃分析时，气溶胶的萃取物不经预处理可直接测定，收集样品的４个滤膜加标后测定的平均回收率为９２８％～１０８％。     

花生中多菌灵残留量的高效液相色谱分析方法的研究

建立了测定花生中多菌灵残留量的高效液相色谱法，以乙酸乙酯提取，乙腈萃取分离，石油醚去酯，乙醇＋水（４＋１）沉淀蛋白质，在Ｒａｄｉｌ＿ＰａｋＣ１８柱上，甲醇＋水（５５＋４５）为流动相，采用外标法进行定量检测，相对标准偏差为０１８％，回收率在８００％～９８０％，最低检测限为０２ｍｇ／Ｌ。     

反相高效液相色谱法测定牙膏中的甘草次酸

采用反相高效液相色谱法测定了牙膏中的甘草次酸。在ＹＷＧ Ｃ１８（４０ｍｍｉ．ｄ．×２５０ｍｍ,１０μｍ）色谱柱上,以Ｖ（甲醇）∶Ｖ（００１ｍｏｌ／ＬＫＨ２ＰＯ４）＝８５∶１５（ｐＨ３０）的溶液为流动相,流速为１０ｍＬ／ｍｉｎ,紫外检测波长为２５４ｎｍ,室温下检测。甘草次酸用甲醇提取。甘草次酸的平均回收率为９９６１％～１０１６７％,样品测试相对标准偏差为１８５％～３１６％。方法操作简便、快速和准确。     

蜂蜜中四环素族抗生素残留量的薄层色谱测定法

残留在蜂蜜中的四环素族抗生素在经Ｓｅｐ－ＰａｋＣ１８小柱固相萃取处理后，用高效正相薄层色谱予以分离，喷雾显色后用紫外灯进行定性分析；使用双波长薄层扫描仪进行定量测定。在蜂蜜中的添加量为００５０×１０－３、０１０×１０－３及０２０×１０－３时，强力霉素（ＤＣ）、土霉素（ＯＴＣ）和四环素（ＴＣ）的回收率分别为９１６％～１００３％、８４５％～１０３１％和７７０％～１０３２％。该法的测定低限可达到１０－３μｇ。     

(Ce_(0.67)Tb_(0.33))MgAl_(11)O_(19)和BaMgAl_(10)O_(17)∶Eu~(2 )荧光体的微波辐射合成及其发光性能

用微波辐射法合成了（Ｃｅ０．６７Ｔｂ０．３３）ＭｇＡｌ１１Ｏ１９（ＰＧ）和ＢａＭｇＡｌ１０Ｏ１７（ＰＢ）两种荧光体，经Ｘ射线粉末衍射分析，其ｄ值和Ｉ／Ｉ０值与ＪＣＰＤＦ３６７３和２６１６３基本一致。计算得到ＰＧ的晶胞参数ａ＝０５５８２ｎｍ，ｃ＝２１８８４ｎｍ；Ｐ－Ｂ的晶胞参数α＝０５６１６ｎｍ，ｃ＝２２６１４ｎｍ。测定了两种荧光体的激发光谱和发射光谱。Ｐ－Ｇ的色坐标ｘ＝０３１６，ｙ＝０５６５；Ｐ－Ｂ的色坐标ｘ＝０１５６，ｙ＝０１０６。与市售同类荧光粉相比，Ｐ－Ｇ的相对发光强度为８８％，Ｐ－Ｂ的相对发光强度为８０％。     

铜试剂显色树脂相分光光度法测定水中痕量Cu(Ⅱ)

提出了在ｐＨ８５０条件下,Ｃｕ（Ⅱ）与铜试剂（ＤＤＴＣ）生成有色配合物,与强碱性阴离子树脂交换吸附,树脂相光度法测定痕量Ｃｕ（Ⅱ）的新方法。结果表明,有色配合物树脂相的最大吸收波长为４２０ｎｍ,Ｃｕ（Ⅱ）含量在０～２０ｍｇ·Ｌ－１范围内符合Ｂｅｅｒ定律,表观摩尔吸光系数为５１×１０４Ｌ·ｍｏｌ－１·ｃｍ１。用于水样中痕量Ｃｕ（Ⅱ）的测定,相对标准偏差小于２３％,加标回收率９７％～１０２％。     

环境水中化学需氧量的FI分光光度法自动在线检测

本文将流动注射分光光度法用于环境废水中化学需氧量（ＣＯＤ）的自动在线检测，方法线性范围在０－１００ｍｇ／Ｌ之间，相对标准偏差＜２％以葡萄糖和苯二甲酸氢钾混合液制备标准溶液，对标准参考水样ＣＯＤ含量（Ｃｒ值）的测定结果表明两者有良好的相关性（Ｒ＝０．９８８０）对环境水样中ＣＯＤ含量的动态变化连续１０ｈ模拟试验，自制的在线过滤装置稳定，未发生堵塞现象；该系统可以较好地跟踪水样中ＣＯＤ浓度的实际变化     

流动注射在线预富集—同步扫描荧光法分析水样中痕量多环芳烃

建立了苯并［ａ］芘和的流动注射在线预富集－同步扫描荧光检测法，方法简便快速。苯并［ａ］芘和的测定下限分别为０２μｇ／Ｌ和００４μｇ／Ｌ。测定的相对标准偏差分别为：７１１％和７５４％。用于实际水样的测定，苯并［ａ］芘的回收率为９０％～１０３３％，为１０３３％～１１６７％，结果满意。     

混合苯中微量砷含量的测定

讨论了混合苯试样的消解前处理过程，提出了消解时间短、反应温和、重现性好的前处理方法。采用二乙基二硫代氨基甲酸银分光光度法测定砷含量，并与原子吸收法和砷斑法进行对照，证明方法可靠。砷含量的平均值为（１３４±００８）×１０－６，相对标准偏差为５９７％，平均回收率为（９３０±３０）％。该法最低检测限为０５μｇ，测定的线性范围为０～２５μｇ。     

Analyses of lepidopteran sex pheromones by mass spectrometry

Lepidoptera, including about 150,000 species in the world, comprise the second largest insect group, and sex pheromones have been identified from virgin female moths of more than 600 species. The chemical structures are simple, but diverse, because species-specific pheromones play an important role in the reproductive isolation of each species. The pheromone content in each female is quite low, and gas chromatography coupled to mass spectrometry (GC-MS) is most frequently utilized to reveal the chemical structure. Almost all pheromone components are straight-chain compounds and are classified into two major groups [i.e. unsaturated C₁₀-C₁₈ fatty alcohols and their derivatives (Type I) and C₁₇-C₂₃ polyenyl hydrocarbons and their epoxides (Type II)]. In addition to the unbranched compounds, some species secrete methyl-branched compounds (e.g., 2-ketones). For the identification of these compounds, determining the positions of the double bond, the epoxy ring, and the methyl group is an important key step. Copious spectral information measured by electron-impact ionization (70 eV) has been accumulated for these compounds. This review therefore deals with their spectral characteristics, namely, diagnostic ions, to apply them to pheromone studies on new target insects.     

GCxGC/TOF MS technique-A new tool in identification of insect pheromones: Analysis of the persimmon bark borer sex pheromone gland

Conventional gas chromatography with electroantennographic detection (GC-EAD) and two-dimensional (GC × GC) gas chromatography using a time-of-flight mass spectrometric detector (TOFMS), were combined to analyse the female sex pheromone gland extract of the persimmon bark borer, Euzophera batangensis. GC-EAD analysis produced two EAD responses in GC areas where no compounds were detected by FID detection. GC × GC/TOFMS analysis of this area indicated the presence of several chemicals, including (Z9,E12)-tetradeca-9,12-dien-1-ol and (Z9)-tetradec-9-en-1-ol, pheromone components of closely related Euzophera species. Spectral characteristics, retention behaviour and the ability to elicit GC-EAD responses imply that both identified unsaturated alcohols are candidates for E. batangensis sex pheromone components. GC × GC/TOFMS facilitated the analysis of complex matrices on a subnanogram level and was shown to have great potential as a powerful tool in the analysis of insect pheromones.     

Insect pheromone components: Use of 13C NMR spectroscopy for assigning the configuration of CC double bonds of monoenic or dienic pheromone components and for quantitative determination of Z/E mixtures

Several insect sex pheromone components and structural analogues have been characterized by ¹³C NMR spectroscopy. The evaluation of the difference between the chemical shift values of the allytic carbons present in the diunsaturated pheromone components and those of the carbons having the same position on the n-alkane chain of the corresponding saturaated compounds was used to assign the configuration of the CC double bonds present into such dienic compounds. The technique avoids the need to use the nuclear Overhausser effect; it allows quantitative evaluation, with good accuracy, of the stereoisomeric composition of mixtures of synthetic monoenic or dienic pheromone components such as (Z)- and (E)-9-tetraceden-1-yl acetate and (Z)- and (E)-9,11-dodecadien-1-yl acetate.     

用于昆虫外激素研究的微量顶空收集及热解吸气相色谱进样方法初探

描述了一个结合项空气流收集与无溶剂热解吸气相色谱进样的方法。用填充PorapskQ的微量注射器作为吸附管进行气流收集。将收集物不经溶剂洗脱直接进行热解吸进样。用人工合成的昆虫外激素化合物反-7-十二碳单烯乙酸酯（E-7-DA）及顺-5,反-7-十二碳二烯乙酸酯（Z-5,E-7-DDA）测定了方法的回收率,初步探索了运用于昆虫外激素分析的可行性,并讨论了提高回收率的途径。     

On-site airborne pheromone sensing

Pheromones and other semiochemicals play an important role in the natural world by influencing the behavior of plants, mammals, and insects. In the latter case, species-dependent pheromone communication has numerous applications, including the detection, trapping, monitoring and guiding of insects, as well as pest management in agriculture. On-site sensors are desirable when volatile organic compounds (VOCs) are used as semiochemicals. Insects have evolved highly selective sensors for such compounds, so biosensors comprising complete insects, isolated organs or individual proteins can be highly effective. However, isolated insect organs have a limited lifetime as biosensor, so biomimetic approaches are needed for prolonged monitoring, novel applications, or measurements in challenging environments. We discuss the development of on-site biosensors and biomimetic approaches for airborne-pheromone sensing, together with biomimetic VOC sensor systems. Furthermore, the infochemical effect describing the anthropogenic contamination of the ecosystem through semiochemicals, will be considered in the context of novel on-site pheromone sensing-systems.     

Analytical studies of Spodopteralittoralis sex pheromone components by electroantennography and coupled gas chromatography-electroantennographic detection

In this paper we present analytical studies of the sex pheromone components of the Egyptian armyworm Spodoptera littoralis (Lepidoptera, Noctuidae) by electroantennography (EAG) and coupled gas chromatography-electroantennographic detection (GC-EAD). EAG responses in three different preparations, using an insect's head, an excised antenna and a live insect, have been recorded. EAG depolarizations of live insects were significantly higher than those elicited by the insect's head or the excised antenna. The responses were dose-dependent. Live insects also allowed regular pheromone stimulations for 40 min with only 38% decrease of the EAG initial depolarization. The synthetic pheromone blend elicited the highest EAG activity (2.0+/-0.3 mV), followed by the major compound (Z,E)-9,11-tetradecadienyl acetate (I) (1.54+/-0.1mV), and the minor components (Z)-9-tetradecenyl acetate (II), (E)-11-tetradecenyl acetate (III), tetradecyl acetate (IV) and (Z)-11-tetradecenyl acetate (V) (1.21-1.32 mV range). (Z,E)-9,12-tetradecadienyl acetate (VI), although not present in the pheromone blend of our strain, also showed an EAG activity (1.32+/-0.09 mV) similar to that of the monoenic components. GC-EAD responses confirmed the composition of the sex pheromone blend, the major response being elicited by the main component I followed by the other minor compounds II-V. The new dienic compound found in the female pheromone gland, (E,E)-10,12-tetradecadienyl acetate (VII), was not electrophysiologically active. Regarding sensitivity, the minimum amount detectable to elicit an antennal response in our GC-EAD system was 15 pg of the major component. In our system, which was built with cheap and easily available materials, no cooling of the effluent at the outlet of the chromatographic column is required.     

An iterative catalytic route to enantiopure deoxypropionate subunits: asymmetric conjugate addition of grignard reagents to alpha,beta-unsaturated thioesters

A highly enantioselective (up to 96% ee) conjugate addition of Grignard reagents, in particular, MeMgBr, to alpha,beta-unsaturated thioesters is provided as well as its application to a diastereo- and enantioselective iterative route to syn- and anti-1,3-dimethyl arrays and deoxypropionate subunits. The versatility of the method is illustrated in the synthesis of (-)-lardolure, a multimethyl-branched insect natural pheromone.     

Asymmetric Synthesis of Spiroketals with Aminothiourea Catalysts

Chiral spiroketal skeletons are found as core structures in a range of bioactive compounds. These natural compounds and their analogues have attracted much attention in the field of drug discovery. However, methods for their enantioselective construction are limited, and easily available optically active spiroketals are rare. We demonstrate a novel catalytic asymmetric synthesis of spiroketal compounds that proceeds through an intramolecular hemiacetalization/oxy‐Michael addition cascade mediated by a bifunctional aminothiourea catalyst. This results in spiroketal structures through the relay formation of contiguous oxacycles, in which multipoint recognition by the catalyst through hydrogen bonding imparts high enantioselectivity. This method offers facile access to spiroketal frameworks bearing an alkyl group at the 2‐position, which are prevalent in insect pheromones. Optically active (2S,5S)‐chalcogran, a pheromone of the six‐spined spruce bark beetle, and an azide derivative could be readily synthesized from the bicyclic reaction product.     

Identification of Biomarker Volatile Organic Compounds Released by Three Stored-Grain Insect Pests in Wheat

Monitoring and early detection of stored-grain insect infestation is essential to implement timely and effective pest management decisions to protect stored grains. We report a reliable analytical procedure based on headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS) to assess stored-grain infestation through the detection of volatile compounds emitted by insects. Four different fibre coatings were assessed; 85 µm CAR/PDMS had optimal efficiency in the extraction of analytes from wheat. The headspace profiles of volatile compounds produced by Tribolium castaneum (Herbst), Rhyzopertha dominica (Fabricius), and Sitophilus granarius (Linnaeus), either alone or with wheat, were compared with those of non-infested wheat grains. Qualitative analysis of chromatograms showed the presence of different volatile compound profiles in wheat with pest infestation compared with the wheat controls. Wheat-specific and insect-specific volatile compounds were identified, including the aggregation pheromones, dominicalure-1 and dominicalure-2, from R. dominica, and benzoquinones homologs from T. castaneum. For the first time, the presence of 3-hydroxy-2-butanone was reported from S. granarius, which might function as an alarm pheromone. These identified candidate biomarker compounds can be utilized in insect surveillance and monitoring in stored grain to safeguard our grain products in future.     

Synthesis of the two enantiomers of the sex pheromone of Diabrotica Undecimpunct at a Howardi and of chiral precursors of other pheromones starting from enantiomerically pure methyl hydrogen (R)-3-methylglutarate

Readily available methyl hydrogen (R)-3-methylglutarate(2) is a useful chiral building block for the synthesis of several biologically active compounds. Enantiomerically pure (R)-2 has been employed to synthesize stereospecifically each of the two enantiomers, 1a and 1b, of 10-methyl-2-tridecanone, the sex pheromone of the southern corn rootworm, Diabrotica undecimpunctata howardi Barber. Compound (R)-2 has been also used to prepare 99% optically pure (R)-3-methyl-1-pentanol (6) and enantiomerically pure (R)-5-methyl-i-tricosyne (7). These compounds are useful building blocks suitable for the further elaboration to other chiral insect pheromones.