裂解气相色谱/质谱联用研究防焦剂CTP的热裂解

采用裂解气相色谱/质谱联用法对防焦剂CTP的热裂解行为进行研究,并对部分热裂解产物的质谱碎裂机理进行探讨。结果表明:防焦剂CTP热裂解适宜条件为温度300℃,时间0.2 min,方式单纯瞬间裂解,固体样品直接进样;不同产地产品的裂解产物具有一致性,热稳定性好;裂解产物共10余个,主峰为原分子,次强峰为邻苯二甲酰亚胺。解析了NIST谱库中不包含的主要裂解产物可能的质谱裂解途径;可根据其中环己硫醇、邻苯二甲酰亚胺、二环己基二硫化物3个裂解产物共同判断防焦剂CTP的存在。     

Py-GC/MS研究防焦剂CTP的热裂解行为

采用裂解气相色谱/质谱联用法对防焦剂CTP的热裂解行为进行研究,并对部分热裂解产物的质谱碎裂机理进行探讨。结果表明：防焦剂CTP热裂解适宜条件为：温度　300 ℃,时间　0.2 min,方式　单纯瞬间裂解,固体样品直接进样;不同产地产品的裂解产物具有一致性,热稳定性好;裂解产物共10余个,主峰为原分子,次强峰为邻苯二甲酰亚胺。解析了NIST谱库中不包含的主要裂解产物可能的质谱裂解途径;可根据其中环己硫醇、邻苯二甲酰亚胺、二环己基二硫化物3个裂解产物共同判断防焦剂CTP的存在。     

裂解气相色谱/质谱联用研究防焦剂CTP的热裂解

正北京橡胶工业研究设计院采用裂解气相色谱/质谱联用法对防焦剂CTP的热裂解行为进行研究,并对部分热裂解产物的质谱碎裂机理进行探讨。结果表明:防焦剂CTP热裂解适宜条件为温度300℃,时间0.2 min,方式单纯瞬间裂解,固体样品直接进样;不同产地产品的裂解产物具有一致性,热稳定性好;裂解产物共10余个,主峰为原分子,次强峰为邻苯二甲酰亚胺。解析了NIST谱库中不包含的主要     

质谱化学离子化法测定氟节胺分子量

研究了氟节胺样品在质谱中不同的离子化方式 ,比较了电子轰击法(EI)和化学离子化法(CI) ,发现用CI -离子化法得到较强的氟节胺离子峰 ,灵敏度最高。     

聚环氧丙烷的电喷雾质谱分析

采用电喷雾质谱（ESI—MS）分析得到了聚环氧丙烷（PPO）的一级质谱和二级质谱。通过正负2种离子化模式计算一级质谱中各分子离子峰m／z的差值为58,证实了单体为环氧丙烷（PO）。并在二级质谱中通过对一些化合物碎片峰的解析,得到了PPO的裂解方式。同时利用碎片分析,推断出此PPO起始剂为丙三醇。     

质谱技术在石油类复杂物质表征中的应用及研究进展

石油类复杂物质的表征一直是质谱学研究的前沿领域之一,其化学组成的精确揭示对于化石类能源的合理及有效利用是非常重要的。介绍了对于石油类复杂物质所采用的"软"质谱技术,对不同质谱技术的局限性做了总结,综述了目前该类物质质谱表征的最前沿进展,认为随着傅里叶变换离子回旋共振质谱(FT-ICR-MS)的发展,离子检测技术已经有了很大突破,但是解析/离子化技术尚不够成熟。     

大气压离子化质谱技术研究N-聚氧乙烯醚衍生物

利用大气压离子化质谱技术 ,采用直接进样方式研究了N 聚氧乙烯醚衍生物的氧乙烯链聚合度 (EO数 )分布 ,并对O 聚氧乙烯醚衍生物及壬基酚聚氧乙烯醚进行了测定。当化合物的分子质量小于 1 0 0 0u时 ,采用大气压化学离子源和大气压电喷雾离子源两种离子化质谱技术均可得到正态的EO数分布曲线 ,最大n值与根据环氧乙烷加入量计算出的平均加成数基本吻合。采用直接进样质谱技术可同步分析含氧乙烯链的不同结构化合物的EO数分布曲线。选择大气压化学离子源检测时 ,样品与溶剂间的极性差异越小越好 ;而采用大气压电喷雾离子源时 ,溶剂极性对EO数的正态分布影响较小。对于EO数较大的化合物 ,宜采用大气压电喷雾源离子化 ,并可观察到多电荷体系 ;调节质谱参数将影响多电荷体系的分布。直接进样质谱技术为含氧乙烯链化合物的EO数分布提供了一条快速、简捷的分析途径。     

拟除虫菊酯类杀虫剂质谱裂解规律的研究

在对多种拟除虫菊酯类杀虫剂的质谱数据进行归纳整理的基础上,分析研究了其质谱裂解规律。结果表明:拟除虫菊酯类杀虫剂在离子化条件下,大多数品种极易裂解。含三元环的羧酸酯类菊酯分子中的羰基与三元环间的碳碳键易发生α断裂,得到含三元环的的特征碎片离子,同时苯环的苄基位发生断裂后得到m/z 181和m/z 208的特征碎片离子,且丰度都较高;醚类结构由于醚键氧原子的吸电子能力较强,得到m/z 183的特征碎片离子。     

蜂蜜的热裂解产物分析

为了研究卷烟添加剂蜂蜜的热裂解产物对卷烟烟气成分的影响,应用热裂解-气相色谱/质谱（Py-GC/MS）联用技术,模拟卷烟燃烧的环境,对蜂蜜在不同裂解温度（300℃、600℃、900℃）和不同氧气浓度（大气环境、10%O2）下的裂解产物进行成分分析。结果表明,在相同裂解氛围和不同裂解温度中,高温时蜂蜜的裂解产物种类多于低温时的;在相同裂解温度和不同裂解氛围中,蜂蜜裂解产物的质量分数不同;蜂蜜在各种不同裂解条件下的主要产物是糠醛、5-甲基糠醛及5-羟甲基糠醛等醛类物质,还产生多种酮类和呋喃类等物质;蜂蜜的大部分热裂解产物是构成卷烟烟气香味的重要成分。     

精油和芳香萃取物中残留苯含量的测定

建立了测定精油和芳香萃取物中残留苯含量的方法,分别考察了静态顶空和直接进样两种进样方式、两种不同固定相的色谱柱、氢火焰离子化检测器(FID)和质谱检测器(MSD)两种检测器。实验得出结论:对于挥发性较大的样品采取直接进样的方式进行测定,不易挥发的样品采用顶空进样方式。实验结果表明,在1×10-6～2.5×10-5浓度范围内,采用不同的组合,残留苯含量均具有良好的线性关系。     

Modern mass spectrometry for coatings

For the analysis of polymers soft ionization mass spectrometry, in which only molecular ions are observed, can provide the complete distribution of chains (length, composition, end-groups) in under ten minutes on microgram quantities of material. Moreover, molecular ion information of neat organic pigments or those present in crosslinked networks can also be furnished. No other analytical technique can supply these data in such a short time. The application of mass spectrometry to the characterization of materials used in today's high performance automotive coatings is presented. These include functional monomers, several acrylic copolymers, organic pigments and an epoxide prepolymer. While there are a variety of mass spectrometric techniques, in this paper we will highlight the techniques that we have found useful for the characterization of organic coating components. The selection of the mass spectrometric technique is dictated by the molecular weight of the material and to a lesser extent the chemical composition. We used potassium ionization of desorbed species (K⁺IDS) performed on a quadrupole mass spectrometer for materials under 1000 Daltons (Da). However, many of the ingredients used in current automotive finishes fall between 1000 and 10 000 Da. For these materials we used a Fourier transform mass spectrometer (FTMS) which is well suited for this mass range and boasts the highest resolution and mass accuracy available. Direct desorption/ionization using a carbon dioxide laser is our standard method of sample introduction. Recently, we coupled a gel permeation chromatograph to our FTMS using an electrospray ionization interface. This hyphenated technique offers one of the most powerful characterization methods for the coatings chemist.     

Mass Spectrometric Identification of Proteins Enhanced by the Atomic Force Microscopy Immobilization Surface

An approach to highly-sensitive mass spectrometry detection of proteins after surface-enhanced concentrating has been elaborated. The approach is based on a combination of mass spectrometry and atomic force microscopy to detect target proteins. (1) Background: For this purpose, a technique for preliminary preparation of molecular relief surfaces formed as a result of a chemical or biospecific concentration of proteins from solution was developed and tested on several types of chip surfaces. (2) Methods: mass spectrometric identification of proteins using trailing detectors: ion trap, time of flight, orbital trap, and triple quadrupole. We used the electrospray type of ionization and matrix-assisted laser desorption/ionization. (3) Results: It is shown that when using locally functionalized atomically smooth surfaces, the sensitivity of the mass spectrometric method increases by two orders of magnitude as compared with measurements in solution. Conclusions: It has been demonstrated that the effective concentration of target proteins on specially prepared surfaces increases the concentration sensitivity of mass spectrometric detectors—time-of-flight, ion trap, triple quadrupole, and orbital ion trap in the concentration range from up to 10⁻¹⁵ M.     

Mass spectra of fatty acid derivatives,of isopropylidenes of novel glyceryl ethers of cod muscle and of phenolic acetates obtained with the finnigan mat ion trap detector

The applicability of the Finnigan MAT Ion Trap Detector (ITD) mass spectrometer for structure determination in some selected fatty acids and their derivatives has been investigated. Isopropylidene derivatives of novel glyceryl ethers isolated from cod flesh and of phenolic acetates are included to indicate the potential for diverse structures and to clarify the protonation of ions. The ITD is a simple and unsophisticated gas liquid chromatographmass spectrometer, but the spectra obtained are in most respects comparable to those from more conventional electron impact mass spectrometers. However, due to the comparatively high background pressure (∼10⁻³ torr) in the ionization chamber of the ITD, there is a tendency for both neutral and ionized molecules to acquire protons from other molecules or fragments through collision. In many cases, the molecular ion was observed as the protonated molecular ion (M+1), as in chemical ionization mass spectrometry. These interactions can be minimized if the sample load is decreased. Phenolic acetates exhibit not only protonation of the molecular ion, but also protonation of stable fragmented neutralmolecules or ions. Presented in part at the AOCS meeting in Philadelphia, May 1985.     

MALDI-TOF-MS: Eine neue analytische Technik zur Charakterisierung von Produkten auf Basis nachwachsender Rohstoffe

MALDI-TOF-MS: A new analytical technique for characterizing products on the base of renewable resources. For the ionization of non-volatile highly polar or high-mass substances a new mass spectrometric technique, the Matrix Assisted Laser Desorption and Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS) has been established which is very suitable for the analysis of oligomeric or polymeric substances synthesized on the base of renewable materials. In the following article the new method is introduced and its performance is demonstrated by examples of surfactants and emulsifiers.     

Hydrogenation of unsaturated fatty esters during isobutane chemical ionization mass spectrometry

Hydrogenation of double bonds was observed to occur during the isobutane chemical ionization mass spectrometry (MS) of unsaturated fatty esters. Chemical ionization (CI) spectra of a series of methyl esters in the C16–C20 carbon range containing 0–4 double bonds showed a variety of ionization characteristics in the molecular ion cluster, including hydride abstraction, charge exchange, protonation and, for the unsaturated fatty acids (FA), hydrogenation of the double bond followed by protonation. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Optimization of the mass spectrometric analysis of triacylglycerols using negative-ion chemical ionization with ammonia

Conditions for the mass spectrometric analysis of triacylglycerols,via direct exposure probe, with ammonia negative-ion chemical ionization were optimized. Triacylglycerols were most favorably ionized, using the reactant gas pressure of approximately 8500 mtorr at the ion source temperature of 200°C with the instrumentation used. Abundant [M-H]⁻ ions were produced under these conditions without the formation of [M+35]⁻ cluster ions, which would interfere with the molecular weight region of triacylglycerols in the spectra. A rapid desorption of the sample from the probe wire is recommended, using a relatively high heating rate (approximately 40 mA s⁻¹), to minimize thermal degradation of unsaturated molecules and the reducing effect of double bonds on the mass spectrometric response of triacylglycerols. Furthermore, the abundance of [M-H]⁻ ion was enhanced by rapid heating, which we found to be important to improve the sensitivity. The appropriate amount of sample applied to the rhenium wire was in the region of 50–300 ng for one determination, i.e., only a few nanograms of a single triacylglycerol is required for production of a reliable spectrum. The reproducibility of the method was good as demonstrated with standards and a raspberry seed oil sample. The described mass spectrometric method is a fast and potentially useful tool for semiquantitative determination of triacylglycerol mixtures of various fats and oils. The discrimination, caused by differences in molecular size and unsaturation of triacylglycerols with 50 to 56 acyl carbons, was negligible under our optimized ionization conditions, thus, no correction factors were needed. These findings have not yet been verified with instruments in other laboratories. However, the present study shows how the analysis of triacylglycerols can be improved, regardless of the instrument, by optimization of the analytical conditions.     

New path in the thermal cracking of triacylglycerols (canola and soybean oil)

Triacylglycerols (TGs) are naturally occurring oils abundant in many crops. A series of batch uncatalyzed thermal decomposition experiments were performed using canola and soybean oils to explore pathways of TG cracking. A detailed gas chromatographic protocol based on mass spectrometric identification and flame ionization quantification was applied to the organic liquid product generated upon cracking. Reaction conditions were identified that resulted in a novel organic liquid product (OLP) composition compared to previously reported work. Under these conditions (temperatures within a 420-440 °C range) a new route for TG thermolysis was discovered in which cracking reactions of original TG-bound fatty acids were nearly complete and led to the formation of 15-25 wt.% C₂-C₁₀ linear saturated monocarboxylic acids and ca. 30% linear alkanes. Less than 2 wt.% C₁₆-C₁₈ fatty acids which were originally present in the feedstocks as glycerol triesters were found in the OLP. These reactions appear to be kinetically controlled due to abundant hydrogen formation. This route provides a significant enrichment of low-MW compounds in the OLP (65-70 wt.% being <C₁₁) and thus may be considered as a new option for the production of replacement products for petroleum-based fuels and chemicals.     

Quantification of Pentafluorobenzyl Oxime Derivatives of Long Chain Aldehydes by GC–MS Analysis

Negative ion mass spectrometric techniques, for compounds having good ionization properties, such as pentafluorobenzyl derivatives, are believed to be more sensitive than positive ion methods. Preparation of PFB oximes of fatty aldehydes from crude lipid extracts is problematic due to the release of free aldehydes from plasmalogens during derivatization. Accordingly, in these studies plasmalogens were removed by silicic acid column chromatography prior to pentafluorobenzyl derivatization. This simple purification step to remove plasmalogens is shown to facilitate the quantification of long-chain aldehydes by analysis of their pentafluorobenzyl oxime derivatives utilizing gas chromatography–mass spectrometry in the negative ion chemical ionization mode. The limit of detection for long chain fatty aldehydes using this method is 0.5 pmol and it is linear over two orders of magnitude. Silicic acid column chromatography followed by electrospray ionization mass spectrometry demonstrated that plasmalogens were removed (the detection limit for this analyses was ≤0.3 pmol). Furthermore, we have exploited the utility and sensitivity of this method to identify increases in hexadecanal and octadecanal in 3-amino-1,2,4-triazole treated human neutrophils. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Negative ion processes for the unambiguous identification of polycyclic aromatic compounds

Electron capture negative ion processes have been applied to the determination of polycyclic aromatic hydrocarbons in complex mixtures using both chemical ionization mass spectrometry and a newly developed gas chromatographic detector. The negative ion chemical ionization mass spectrometric technique allows isomeric PAH compounds to be differentiated on the basis of relative electron affinities. Compounds which have electron affinities > 0.5 eV form molecular anions while compounds with lower electron affinities are not ionized. The new gas Chromatographic detector also enables isomeric PAH to be differentiated as a function of relative electron affinities. This detector exhibits continuous tunability, allowing the gas phase reactions to be controlled to a greater degree than in the NICI experiment. This flexibility allows a wider variety of compounds to be differentiated using the g.c. detector. Additionally, the g.c. detector may be operated either as a conventional electron capture detector or as an argon ionization detector, which has virtually universal response to organics.     

Fourier Transform Mass Spectrometry: The Transformation of Modern Environmental Analyses

Unknown compounds in environmental samples are difficult to identify using standard mass spectrometric methods. Fourier transform mass spectrometry (FTMS) has revolutionized how environmental analyses are performed. With its unsurpassed mass accuracy, high resolution and sensitivity, researchers now have a tool for difficult and complex environmental analyses. Two features of FTMS are responsible for changing the face of how complex analyses are accomplished. First is the ability to quickly and with high mass accuracy determine the presence of unknown chemical residues in samples. For years, the field has been limited by mass spectrometric methods that were based on knowing what compounds of interest were. Secondly, by utilizing the high resolution capabilities coupled with the low detection limits of FTMS, analysts also could dilute the sample sufficiently to minimize the ionization changes from varied matrices.