Prediction of release ratios of multicomponent pheromones from rubber septa

A method has been developed to predict the release ratio of the components of blends of alcohols, acetates, and/or aldehydes from rubber septa. The calculations of predicted release ratios are based on the relative vapor pressures of the components. The relative vapor pressures of the compounds were calculated from their retention indices on a liquid crystal capillary gas chromatographie column. The correlation between the theoretically predicted and experimentally determined ratios was very good. Thus, formulations can be prepared that will release a desired ratio of the components of a multicomponent pheromone blend.Mention of a commercial or proprietary product does not constitute an endorsement by the USDA.     

Insect sex pheromones: Determination of half-lives from formulations by collection of emitted vapor

A new method for determining half-lives for the evaporation of sex pheromones from formulations has been developed. A previously unexploited mathematical relationship makes possible the determination of half-lives of over 1000 days by collecting evaporated pheromone for 1–4 hr and measuring the amount collected and the amount left in the formulation. Purified nitrogen flows over the test material and the evaporated pheromone is qualitatively collected on an adsorbent of 80–100 mesh silica gel silanized with octadecyltrichlorosilane. Quantitation is by gas chromatography. Quantitative mass balance was achieved and half-lives determined by this new method are in agreement with half-lives previously determined by measuring the amount of pheromone left in septa after a sequence of time intervals. Previously undetermined half-lives for acetates and alcohols are reported.     

Insect sex pheromones

The half-lives (tin1/2) of acetate sex pheromones andn-alkyl acetates were determined on either or both West Co. and Arthur H. Thomas Co. natural rubber septa. These septa gave equal half-lives. Thet _1/2 values covered a large range: e.g.,t _1/2 for decyl acetate was 5 days and that for pentadecyl acetate was 1353 days. The expected linear relationship between Int _1/2 versus the number of carbon atoms was found for the six acetates fromn-decyl to pentadecyl, but thet _1/2 of hexadecyl acetate was only 478 days. This nonlinearity in the plot is attributed to the presence of polymer cross-links which create molecular size cages and produce an effect similar to that produced in gel permeation chromatography wherein large molecules elute faster than smaller ones. Thet _1/2 of 4 monounsaturated acetates were close to thet _1/2 for the corresponding saturated acetates, but this relationship may not be general. The half-life of one nonconjugated diunsaturated acetate was much less than that for the corresponding monounsaturated acetate, whereas the half-life of another nonconjugated diunsaturated acetate was similar to the half-life of the corresponding monounsaturated acetate. Thet _1/2 values determined for the pheromones may be used to estimate evaporation rates, the length of time the evaporation rates will be within a given range, and, with multicomponent pheromones, the ratio of components in the vapor.Mention of proprietary products does not constitute an endorsement by the USDA.     

Sex pheromone of the avocado pest,Amorbia cuneana (Walsingham) (Lepidoptera: Tortricidae)

The major volatile components in the extract of the female sex pheromone gland ofAmorbia cuneana consisted of (E,E)- and (E,Z)-10,12-tetradecadien-1-ol acetates. The identification was based on electroantennogram bioassay of gas Chromatographic effluent from sex pheromone gland extract, relative retention times on polar and nonpolar gas chromatographic columns, chemical degradation (ozonolysis, saponification), mass spectrometry, chemical synthetic methods, and field tests. Based on mass spectrometry and retention times by capillary gas chromatography, traces of (E)-10-tetradecen-1-ol acetate and 1-tetradecanol acetate were also present in the extract. Traps baited with a combination of synthetic (E,E)- and (E,Z)-10,12-tetradecadien-1-ol acetates caught more males than did traps baited with females.This paper reports the results of research only. Mention of a commercial product in this paper does not constitute a recommendation by the U.S. Department of Agriculture.     

Insect sex attractants: XI. analysis ofcis andtrans isomers of fatty alcohol acetates by gas chromatography

A gas chromatographic procedure was devised for the analysis of geometric isomers of dodecenyl acetates, tridecadienyl acetates, tetradecenyl acetates and hexadecenyl acetates. Use of diethylene glycol succinate in a 300 ft capillary column permitted the separation of nine pairs ofcis-trans isomers and four geometric isomers of 5,9-tridecadienyl acetate. Data are presented on the isomeric composition of alkenyl acetates prepared by three different stereospecific reactions and by elaidinization.     

Chromatographic separation of the stereoisomers of α-tocopherol

The diastereoisomers of2-ambo-α-tocopherol were completely separated as TMS ethers by gas chromatography on a 115 m × 0.25 mm glass capillary column coated with SP2340, at a column temperature of 195 C. In the same way,all-rac-α-tocopherol was separated into four peaks, corresponding to the four racemates present, and having the same retention ratios as the four diastereoisomers of 4′-ambo-8′-ambo-α-tocopherol (produced by the hydrogenation of natural α-tocotrienol). Retention data and relative peak areas for the diastereoisomers of the synthesized α-tocopherols and several commercial products were determined. Limited data on the isomers of other tocopherols also are reported.     

Capillary gas chromatographic analyses of headspace volatiles from vegetable oils

Eight different vegetable oils obtained commercially were analyzed for volatiles by capillary gas chromatography (GC). Volatiles generated in a GC static headspace sampler at 180 C were injected automatically onto a chemically bonded capillary column. Only a small number of GC peaks of low intensity were observed in the fresh samples, which varied in peroxide values from 0.2 to 3. Several major peaks were evident in the oils aged eight and 16 days at 60 C with peroxide values ranging from 16 to 65. Thirty-four GC peaks were identified on the basis of relative retention time of reference compounds and on the basis of gas chromatography-mass spectrometry (GC-MS). Volatile compounds identified were those expected from the autoxidation of principal unsaturated fatty acid components of each vegetable oil tested. The relative concentrations of volatile components increased with the level of oxidation as determined by peroxide value. Presented at the AOCS Meeting in Chicago, May 1983.     

溶胶-凝胶法制备用于快速分析的单油酸山梨醇酐酯毛细管气相色谱柱

采用溶胶-凝胶法制备毛细管气相色谱柱,不仅制备工艺简单,制柱时间较传统工艺大为缩短,而且制备的色谱柱性能良好.本研究用该法制备了以单油酸山梨醇酐酯为固定相的毛细管气相色谱柱.色谱柱虽然较短,只有3.5 m,但该色谱柱显示了良好的分离能力,醇、酚、胺、游离羧酸、酯、烃等都可以在该柱上得到很好的分离.此色谱柱同时显示了良好的热稳定性与较高的柱效,理论塔板数达2 274/m.由于色谱柱较短,该柱适用于气相色谱中的快速分析.     

A temperature-dependent model for predicting release rates of pheromone from a polyethylene tubing dispenser

A model was developed to describe release of two formulations of tetradecenyl acetates in Shin Etsu polyethylene tubing pheromone dispensers. Change in pheromone column length in the polyethylene tubing was modeled bydl/dt=l ... (a+bT)/dt (wherel is column length,t is time interval, andT is average temperature for that time interval). Regression of the natural log of relative change in liquid length against time interval and accumulated day degrees in orchards produced the coefficientsa andb. The model was validated by comparing predicted and actual liquid length remaining in field-aged dispensers, as well as measuring release rates by using gas chromatography. Mean daily orchard temperatures and measurement of column length of dispensers on a single date were used to accurately predict column length within 15%, after six months. Predictions of instantaneous release rate were also made from this model, and other possible model uses and limitations are discussed.     

Identification of some volatile compounds in the odor of fecal pellets of the rabbit,Oryctolagus cuniculus

A study has been made of the volatile constituents in the vapors collected from fecal pellets of wild rabbits,Oryctolagus cuniculus. Measurements of changes in the heart rates of adult male rabbits exposed to the effluent of a gas chromatographic capillary column were used to indicate the presence of compounds which may be of behavioral significance. Combined with the use of high-resolution columns in gas chromatography and gas chromatography-mass spectrometry, this approach has implicated several classes of compounds, including volatile fatty acids and phenols, which in certain absolute or relative concentrations may be involved in the formation of signals of territorial importance.     

Lipid composition ofNeurospora crassa

The lipids ofNeurospora crassa, isolated in pure form from freeze-dried mycelium, were found to contain squalene, sterol esters, triglycerides, free fatty acids, geranylgeraniol, free sterols, carotenoids, cardiolipin, phosphatidyl ethanolamine, phosphatidyl choline, phosphatidyl serine, and phosphatidic acid. The above compounds were isolated in pure form by column and thin layer chromatography and were characterized by infrared spectroscopy and chromatographic mobilities. Fatty acid moieties were characterized by gas liquid chromatographic retention times of their methyl esters relative to those of authentic standards. The fatty acid composition of the triglycerides was found to be similar to that of phosphatidic acid, cardiolipin, and lecithin.     

轻汽油醚化产物的气相色谱分析

采用PONA柱和一段极性毛细柱串联而成的毛细管色谱柱分析轻汽油及其醚化后产物的全组成,该方法的相对标准偏差为3.33%,主要组分的相对误差为0.99%。该分析方法具有准确、快速、操作简单等优点。     

Vapor–liquid equilibria for benzene/polybutadiene and cyclohexane/polybutadiene systems at 333, 355, and 373 K using gas chromatography

A perturbation chromatography apparatus has been designed and constructed for determining the vapor–liquid equilibrium between a two-component (solvent/helium) vapor phase and a two-component (polymer/solvent) liquid phase. The apparatus performed very well, giving reproducible and reliable results that agree with independent, previously reported studies. All tests of the equipment indicated that it was successful in meeting the conditions of low column pressure drop, small perturbations, and slow flow rate that are required for perturbation chromatography. Binary polymer/solvent data were obtained for polybutadiene (PBD)/benzene or polybutadiene/cyclohexane systems at solvent partial pressures to 40 kPa and for n-hexane at infinite dilution, all at the three temperatures of 333.15, 355.00, and 373.15 K. The experimental data for each system can be represented within experimental error by the Flory–Huggins polymer solution theory using a single binary interaction parameter that is independent of temperature and concentration.     

Determination of the vapor pressures of moth sex pheromone components by a gas chromatographic method

The vapor pressures of decyl acetate, five decenyl acetate isomers, (Z)-7-dodecenyl acetate, and (Z)-9-tetradecenyl acetate have been determined at three to six temperatures in the interval 25–45 °C by a gas Chromatographic method suitable for accurate measurements of the low vapor pressures of moth sex pheromone components at biologically relevant temperatures. The vapor pressure values at 30.5 °C are 3.80 Pa for decyl acetate, 4.08–5.40 Pa for the decenyl acetate isomers, 0.562 Pa for (Z)-7-dodecenyl acetate, and 0.094 Pa for (Z)-9-tetradecenyl acetate. The vapor pressures of the decenyl acetates show a small but significant dependence on the double bond position. Four of the compounds in this study, 10Ac,Z5–10Ac,Z7–12Ac, andZ9–14Ac have recently been identified as sex pheromone components of the turnip moth,Agrotis segetum. Large differences between the mole percentages of the component as found in liquid extracts of female abdominal tips and the corresponding mole percentages in the vapor phase are predicted.     

The Determination of Fatty Acid Primary Amides by Capillary Gas Chromatography

A method has been developed for the determination of 12 primary amides of long-chain fatty acids by capillary column gas chromatography. The method uses no derivatization or sample preparation other than extraction of the sample. A variety of commercial amidecontaining materials have been analyzed successfully. The amides, along with other soluble materials, are first separated from the host using refluxing 2-propanol containing an internal standard. The fatty acid amides are then identified and measured by gas chromatography over a programmed temperature range of 200 to 260 C. The chromatograms obtained show sharp peaks, unique retention times and acceptable reproducibility for quantitation.Cis- trans isomers of several of the fatty acid amides were tested and found to be resolved under the conditions employed.     

Studies on the fatty acid composition of crayfish lipids

The fatty acid composition of carcass and exoskeleton lipids was determined for the freshwater crayfishOrconectes rusticus. Lipid fractions were isolated by column and thin-layer chromatography. Fatty acid methyl esters and alcohol acetates were then prepared and analyzed by gas-liquid chromatography. Peak identities were established from retention time data for methyl esters, hydrogenated methyl esters, and saturated, monoene, diene, and polyene methyl esters separated as acetoxy-mercuri-methoxy derivatives. Minor component acids were estimated from their relative compositions in these fractions. Presented at the symposium honoring J. B. Brown, AOCS meeting in Chicago, 1964.     

苯噻酰草胺的填充柱气相色谱分析

对苯噻酰草胺进行填充柱气相色谱分析方法研究。经试验,采用5%SE-30/Chromosorb w aw DMCS为固定相的填充柱,磷酸三苯酯为内标,成功地进行苯噻酰草胺气相色谱分析,并与行标HG3719-2003、HG3720-2003的液相色谱法、毛细管气相色谱法进行比较,取得一致结果。     

气相色谱法测定反应液中N,O-双(三甲基硅基)乙酰胺的含量

建立了气相色谱法测定N,O-双(三甲基硅基)乙酰胺反应液的分析方法,采用SE-30弹性石英毛细管柱,柱温120℃,以邻二氯苯为内标物,以样品的进样量对样品峰面积与内标物的峰面积之比进行线性回归,各组分线性关系良好,相关系数为0.9991～0.9995。测定结果的相对偏差为1.54%。     

离子液体作为气相色谱固定相的参数测定

将疏水性离子液体[BMIM]PF6用于气相色谱固定相中,检测分离环己烷、甲苯、邻二甲苯混合有机溶剂,并与邻苯二甲酸二壬酯填充柱对这3种物质的分离效果进行比较。实验结果表明：邻苯二甲酸二壬酯柱虽然也能将这3种物质分开,但各物质出峰太慢、保留时间长、峰高太低,而疏水性离子液体[BMIM]PF6柱对这3种物质有很好的分离效果,各物质保留时间缩短、峰高增强,由此得出离子液体作为气相色谱固定相对分离这类有机物的优势。     

环氧氯丙烷中有机杂质组分的气相色谱法测定

介绍了在环氧氯丙烷国家标准制定过程中对环氧氯丙烷中有机杂质组分测定方法的改进。通过采用毛细管柱气相色谱法,对分离条件、毛细管柱选择等进行了试验和讨论。试验结果表明,采用毛细管柱气相色谱法,选用N2作为载气,分流比50∶1,并采用程序升温:柱初温40℃(保持5 min)→10℃/min→180℃(保持30 min)的条件下可获得更好的分离效果及准确度,该方法测得各杂质组分的相对标准偏差为0.0113%~0.0377%,回收率为93.3%~102.9%。能满足生产中质量控制和产品出厂分析的需要,保证了国家标准分析方法的先进性。