Capillary column gas chromatography/mass spectrometry of explosives

Gas chromatography/mass spectrometry (GC/MS) using a 15 m long capillary column has been employed in our laboratory for the analysis of explosives. The technique is suitable for most of the common military explosives. Nitroaromatic compounds like TNT were analysed easily and with high sensitivity and so were the volatile nitrate esters like glycerine trinitrate. Success was also achieved in the analysis of PETN and RDX, which had previously been reported to pose problems under GC conditions. Tetryl was shown to decompose during the analysis but its decomposition product was well defined and could serve as evidence to the presence of tetryl. The method was successfully applied to post-explosion debris from actual cases.     

HPLC-MS Examination of Impurities in Pentaerythritol Tetranitrate

Pentaerythritol tetranitrate (PETN) has trace homolog impurities that can be detected by high-performance liquid chromatography–mass spectrometry. Consideration of observed impurity masses and candidate structures based on known pentaerythritol impurities allows identification of 22 compounds in the data. These are all consistent with either fully nitrated homologs or derivatives substituted with methyl, methoxy, or hydroxyl groups in place of a nitric ester. Examining relative impurity concentrations in three starting batches of PETN and six subsequently processed batches shows that it is possible to use relative concentration profiles as a fingerprint to differentiate batches and follow them through recrystallization steps.     

Gas production from thermal decomposition of explosives: Assessing the thermal stabilities of energetic materials from gas production data

Abstract

The gas formation associated with the thermal decompositions of nineteen energetic materials was determined at three temperatures (120°C, 220°C and 320°C). Although there was considerable variability within classes, among the largest producers of gas were the nitrate esters. PETN (pentaerythritol nitrate) generated about 6.3mole gas per mole, while nitrocellulose, produced almost no gas. Second in gas production were the nitramines, followed by nitroarenes and lastly, energetic salts. NTO (5-nitro-2, 4-dihydro-3H-1, 2, 4-triazol-3-one), which does not fit into the four main classes of energetic materials, exhibited gas production (2.13 mole gas per mole NTO) comparable with some nitroarenes and the energetic salt, ammonium dinitramide (ADN). For selected compounds gas evolution data was used to construct first-order plots, from which Arrhenius parameters were determined and compared with previously reported values.     

Post explosion analysis of explosives by mass spectrometric methods

The Analysis of trace amounts of explosives from post-explosion debris–one of the most difficult problems in forensic chemistry-is still carried out in many laboratories by chromatographic methods only. In recent years several new methods have been applied to the analysis of explosives. These include mass spectrometric methods (GC/MS, LC/MS and MS/MS) and NMR methods. The possible application of these methods to post-explosion analysis is discussed and various aspects of the techniques are reviewed and compared. The choice of capillary column GC/MS as a routine method in the Israel Police laboratory is explained and examples from actual cases are given.     

Analysis of explosives by nuclear magnetic resonance spectrometry

In order to evaluate the applicability of NMR to the analysis of explosives, the method was used to analyse explosives from actual cases. The results were then compared with results from other analytical methods, mainly TLC and GC/MS. For unexploded samples NMR was found to be a simple, fast and reliable method, often allowing the identification of mixtures without pre-separation. Some post-explosion samples were also successfully analysed by NMR. Although sensitivity problems still exist, NMR showed a surprisingly promising prospects for the difficult field of post-explosion analysis.     

橡胶在季戊四醇酯基础油中溶胀规律的理论模型

采用季戊四醇分别和不同碳数脂肪酸合成一系列单酸季戊四醇酯,测定5种橡胶在不同单酸季戊四醇酯中的体积变化率,探索可解释和预测橡胶在季戊四醇酯中溶胀趋势的最佳理论模型。结果表明：季戊四醇酯的摩尔体积(Vm)和非极性参数(NPI),以及季戊四醇酯与橡胶之间的Hildebrand一维溶解度参数差值(Δδ)和能量差(Ra)在解释和预测季戊四醇酯对橡胶的溶胀规律方面皆具有一定的局限性。提出了抗溶胀参数(ΔAS)可解释和预测季戊四醇酯对5种橡胶的溶胀趋势,以及同碳数正、异构酯对5种橡胶溶胀的差异,弥补和修正了Vm、NPI、Δδ和Ra的不足。     

AN INVESTIGATION OF TWO HOMOLOGOUS SERIES OF CARBOXYLIC ACIDS IN BLACK TRONA WATER FROM THE GREEN RIVER BASIN

Two series of carboxylic acids were Identified in the dialysate from a sample of Black Trona Water from the Green River Basin of Wyoming. One of the series consists of straight-chain dicarboxylic acids ranging in carbon number from four to fourteen. This series had been observed by previous workers. The other series, much less abundant than the dicarboxylic scids, appears to be a series of homologous tricarboxylic acids that are derivatives of succinic acids. The structures of these compounds were determined by analysis of the mass spectra of their methyl esters and trideuteromethyl esters. Definitive biological precursors of this unusual class of compounds could not be assigned     

全二维气相色谱-飞行时间质谱分析直馏柴油馏分中硫化物的分子组成

The solid-phase extraction using Pd-Al2O3 as the stationary phase was employed to pre-separate the sulfur compoundsin straight-run diesel. The isolating effect was evaluated quantitatively by gas chromatography with a sulfur chemiluminescencedetector to harvest a satisfactory result. The identification of the structure of sulfur compounds by comprehensivetwo-dimensional gas chromatography coupled with the time-of-flight mass spectrometry indicated that cyclo-sulfides,benzothiophenes, dibenzothiophenes, dihydro-benzothiophenes and tetrahydro-dibenzothiophenes were included in straightrundiesel obtained from the Arab medium crude （AM）. A total of 259 individual compounds were detected and their molecularstructures were identified. The analytical method was approved as an effective way to characterize the composition ofsulfur compounds, which reduced the interference of other compounds, facilitated the data presentation and provided moredetailed information about molecular composition of sulfur compounds.     

AN INVESTIGATION OF TWO HOMOLOGOUS SERIES OF CARBOXYLIC ACIDS IN BLACK TRONA WATER FROM THE GREEN RIVER BASIN

ABSTRACT

Two series of carboxylic acids were Identified in the dialysate from a sample of Black Trona Water from the Green River Basin of Wyoming. One of the series consists of straight-chain dicarboxylic acids ranging in carbon number from four to fourteen. This series had been observed by previous workers. The other series, much less abundant than the dicarboxylic scids, appears to be a series of homologous tricarboxylic acids that are derivatives of succinic acids. The structures of these compounds were determined by analysis of the mass spectra of their methyl esters and trideuteromethyl esters. Definitive biological precursors of this unusual class of compounds could not be assigned     

季戊四醇酯合成工艺研究进展

总结了几种合成季戊四醇酯的方法。重点介绍了酯化反应合成季戊四醇酯的催化剂和工艺的研究进展,并同时阐述了不同催化剂的催化机理。研制高活性,可循环使用和后处理简单的催化剂仍然是酯化反应合成季戊四醇酯的发展目标。     

Stability and Degradation Processes of Pentaerythritol Tetranitrate (PETN) on Metal Oxide Surfaces

The chemical stability of pentaerythritol tetranitrate (PETN) when placed in physical contact with metal oxides is investigated. In this study, PETN was placed on the surfaces of a range of microcrystalline metal oxides including MnO₂, CuO, MoO₃, WO₃, Bi₂O₃, SnO₂, and Fe₂O₃ in coverages of 1–3.5 monolayers by a wet impregnation technique. Samples were then placed in a controlled temperature environment at 50°C and checked periodically for the presence of decomposition products using liquid chromatography. PETN proved to be inert over all of the oxides except MoO₃, which showed the relatively rapid evolution of a brown gas over a period of 48 h. Analysis of the evolved gas indicated that it is primarily NO₂ along with N₂O₄, N₂O, and CO₂.     

Characterization of Nitrogen Compounds in Vacuum Residue and Their Structure Comparison with Coker Gas Oil

In this study, the heteroatom classes and molecular structures of nitrogen compounds in vacuum residue are characterized by the electrospray ionization(ESI) Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS) combined with the Fourier transform infrared(FT-IR) spectroscopy. The results demonstrate that three basic nitrogen compounds, N1(in which a molecule contains one nitrogen atom, similarly hereinafter), N1O1 and N2, are identified by their positive-ion mass spectra, and three non-basic nitrogen compounds, N1, N1O1, and N1S1, are characterized by their negative-ion mass spectra. Among these nitrogen compounds, the N1 class species are the most predominant. Combined with the data of ESI FT-ICR MS and FT-IR, the basic N1 class species are likely alkyl quinolines, naphthenic quinolines, acridines, benzonacridines, while the abundant non-basic N1 class species are derivatives of benzocarbazole. In comparison with CGO, the N1 basic nitrogen compounds in VR exhibit a higher average degree of condensation and have much longer alkyl side chains.     

Effect of skin contact on the free and bound aroma compounds of the white wine of Vitis vinifera L. cv Narince

Free and glycosidically bound aroma compounds of the Narince wines and the effect of skin contact treatment (15 °C, 12 h) on aroma composition have been investigated during two vintages. Free and bound aroma compounds were extracted with dichloromethane and Amberlite XAD-2 resin, respectively, and then analysed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS). According to the results obtained in both vintages, Narince wines were characterized by the presence of high level of fermentative aroma compounds (higher alcohols, fatty acids, and esters, respectively), and skin contact treatment increased the total concentration of free and bound volatiles.     

Increasing the Thermooxidative Stability of Pentaerythritol Esters and Synthetic Fatty Acids

A common drawback of high-temperature oils based on pentaerythritol esters and C₅–C₉ synthetic fatty acids (SFA) is low resistance to oxidation in the presence of metals at high temperatures. In this respect, the possibility of increasing the temperature limit of the efficiency of pentaerythritol ester is being intensively investigated: by removal of contaminants that initiate oxidation; improvement of the production technology; addition of more thermostable components, usually oxidation inhibitors [1–4].     

新戊基多元醇酯的制备及其黏度特性

制备了一系列新戊基多元醇酯,利用傅里叶变换红外光谱(FT-IR)、气质联用(GC-MS)和原子发射光谱(AES)对合成酯进行了分析鉴定,并测定其运动黏度。结果表明:合成了酯化率较高且杂原子很低的新戊基多元醇酯,季戊四醇二脂肪酸混合酯由五种组分构成;其运动黏度随脂肪酸碳原子数、长链脂肪酸、异构酸、长链异构酸、醇羟基数含量增大而逐渐增大;其黏度指数随脂肪酸碳原子数、长链脂肪酸、长链异构酸和醇羟基数含量的增大变化不明显,而随异构酸含量的增加逐渐降低。     

Aspects of the behavior of some pentaerythritol ester base synlubes for turbo-engines

In this work a series of pentaerythritol esters have been synthesized. Dean Stark apparatus has been used to measure the water separated periodically as one of the resultants giving an indication about reaction progress. Elementary analyses, mean average molecular weight, i.r., viscosity, density and pour point have been determined for the prepared esters.Some physico-chemical behaviors and correlations have been deduced to characterize the prepared esters. Moreover, they shed the light on their suitability as base oils which may be used in formulations according to French Air specification 3514 (Nato 0–150) as compared with the commercial oil sample (Trubonycoil 13B) used in this respect.     

INTERACTION OF SUPERCRITICAL METHANOL AND WATER WITH ORGANIC MATERIAL IN GREEN RIVER OIL SHALE

A series of experiments to study the interaction of supercritical methanol and water with Green River oil shale was performed. The volume percentage of methanol (CH₃0H) in water was varied. The temperature was held constant at 400°C. The products were fractionated and characterized with infrared spectroscopy and elemental analyses. A ¹³CH₃0H experiment was carried out and 13C nuclear magnetic resonance (NMR) analysis was used to prove the incorporation of methanol into the products. The methyl esters resulting from the incorporation were isolated and characterized by high resolution mass spectrometry. The experiments on a model compound and gas chromatographic/mass spectral (GC/MS) analysis of the product showed that methanol can react with carboxylic acids found in Green River oil shale to form methyl esters. However, this incorporation of methanol into the product oil from supercritical fluid extraction was found to be not sufficient to account for the increased oil yields, The role of methanol in these experiments on Green River oil shale is discussed.     

Vapor pressure of explosives

New vapor pressure data is presented for RDX, PETN, TNT, nitroglycerin, and ammonium nitrate. By comparison with the data of previous workers, it has been possible to calculate global vapor pressure expressions which are valid over a wide range of temperatures.     

MECHANISMS OF GASOLINE DEPOSIT FORMATION IN ENGINE INDUCTION SYSTEMS, CHARACTERIZATION OF PRODUCT REACTION BETWEEN BENZOTHIOPHENE OXIDES AND BASIC NITROGEN AND NAPHTHENIC COMPOUNDS

To evaluate the role of different types of gasolines compounds in the deposit formation process in engine admission systems, a series of reactions between toluene, octene and benzothiophenes derivates and benzothiophene oxides have been studied. To continue with the study of establishing the funtionalities more prone to react towards deposit formation, reactions between benzothiophene oxides with aniline mixture and cyclopentane were carried out under reflux conditions, using carbon tetrachloride as solvent. Samples of the reaction mixture were taken after 24 hr and identification was made by pyrolisis/gas chromatography/mass spectrometry (Py/GC/MS) and mass spectrometry/mass spectrometry (MS/MS). The aniline sample reaction showed the formation of new products at masses m/z 246, 260 and 274 daltons which were identified as diphenildisulfur derived compounds. The cyclopentane sample reaction showed a product at m/z 386 daltons, characterized by MS/MS as a new intermediate compound generated during the formation of naphthobenzothiophenes. No reaction product with anilines was detected. Possible structures of these products are proposed based on MS/MS mapping experiment.     

利用不同质谱技术分析鉴定金刚烷类化合物

金刚烷类化合物因在油气勘探领域具有重要的应用价值受到研究人员的广泛关注。由于具有复杂的分子结构和数量众多的同分异构体，目前对于某些金刚烷类化合物的定性结果还存在争议。通过气相色谱—质谱联用法、气相色谱—三重四极杆质谱联用法和全二维气相色谱—飞行时间质谱联用法，开展了烷基取代单金刚烷衍生物的定性研究，对3-甲基-1-乙基单金刚烷和3，5，7-三甲基-1-乙基单金刚烷在不同类型质谱色谱图中的出峰位置进行了确认。此外，利用MASS FRONTIER软件推断了3，5，7-三甲基-1-乙基单金刚烷在电子轰击离子源作用下的碎裂机理以及产生的特征离子。