TGA和Py-GC/MS研究不同氛围下烟草的热失重和热裂解行为

应用热重红外联用技术(TG-FTIR)和热裂解气相色谱-质谱联用技术(Py-GC/MS)对卷烟烟丝的热失重和热裂解行为及其裂解产物进行研究.采用热重分析法测定不同气氛下卷烟样品的热失重(TG)、微商热重(DTG)曲线,以及热裂解过程中H2O、CO2、CO、NH3和CH4等气体物质的释放量.结果表明,裂解气氛不同可以显著...     

裂解-气相/质谱法分析木屑物证

木屑是一种在各种案件现场中出现几率较高的微量物证,但由于其化学组成复杂、难溶,高分子组分之间的差异不显著,所以一直未建立有效的鉴定方法.采用裂解-气相/质谱技术(PY-GC/MS)对不同树种木屑难溶物进行分析,结果发现:不同树种木屑难溶物的总离子流图特征相似,即每种木屑难溶物的总离子流图中都有一组特征峰.但个别组分有差异.     

不同涤纶绳索纤维的PY-GC/MS定性分析

利用裂解-气相色谱/质谱联用法对9个不同产地、不同规格的涤纶绳索样品进行鉴别分析.首先通过优化选择,确定试验条件,即裂解温度为550℃、裂解时间为6 s时,柱程序升温条件为50℃(1 min)20℃/min→250℃(10 min).在此条件下可最大限度的显示涤纶裂解产物的特征.9个样品的裂解分析结果显示,涤纶的主要裂解产物有13种,其中特征裂解产物为苯甲酸(相对强度100%)、苯甲酸乙烯酯、联苯、苯等.虽然9个涤纶绳索有相同的裂解特征,但个别裂解产物及各特征裂解产物的相对含量有所不同.这一差异可以作为不同规格、不同产地涤纶绳索分析鉴别的依据.     

型煤中硫的还原热解MS和GC/MS分析

以煤和生物质为主要原料的商用型煤为研究对象,采用还原热解（AP-TPR）在线质谱（MS）联用,以及离线色谱/质谱（GC/MS）分析法,定性和定量研究了家用型煤释放的含硫化合物。不同组成的型煤表现出各自不同的硫释放特性。对于生物型煤来说,仅检测到少量二烷基硫醚和脂肪硫醇的存在。褐煤型煤检测到种类最多的有机硫化物。在高阶煤制成的型煤中没有检测到氧化态的硫化物,其典型特征是存在一些噻吩类硫化物。     

Structural characterization and sequence distributions of polysiloxanes using pyrolysis MS/MS

Novel polysiloxanes, with 4-(dialkylamino)pyridine substituents, are characterized by pyrolysis tandem mass spectrometry. These polymers form abundant cyclic oligomeric ions under both desorption electron ionization (DEI) and desorption chemical ionization (DCI) conditions. Product MS/MS spectra of the cyclic ions reveal characteristic fragmentations under low energy collision activated dissociation. Protonated cyclic oligomers higher than the pentamer are mainly due to the proton bound dimers of lower oligomeric units. The cyclic oligomers are shown to have proton affinities greater than 1000 kJ/mole. It is proposed that thermal depolymerization occurs through an intramolecular siloxane bond rearrangement, which is in agreement with a previously proposed "loop mechanism". Markovian statistical calculations are applied to the DCI mass spectral data in order to determine the sequence distribution of siloxane copolymers. Application of this method show that the monomers in the copolymers examined are non-randomly distributed.     

Study of the thermal degradation of flame-retardant polyester GFRP using TGA and TG-FTIR-GC/MS

Journal of Thermal Analysis and Calorimetry - The thermal degradation behaviors of commercial flame-retardant unsaturated polyester glass fiber-reinforced plastic (polyester GFRP) containing...     

Thermal-oxidative induced degradation behaviour of polyoxymethylene (POM) copolymer detected by TGA/MS

The influence of reprocessing and thermooxidative ageing on the degradation behaviour of a commercial poly(oxymethylene) (POM) copolymer was studied by means of thermogravimetric analysis (TGA) under nitrogen and air atmosphere. Five heating rates were used to evaluate activation energies at several degrees of conversion. TGA-measurements were accompanied by simultaneous monitoring of the evolved gases with a mass spectrometer (MS) coupled to the TGA-furnace outlet. The mass spectra showed that the main degradation product was formaldehyde and that in air further formation of water was detectable. In nitrogen atmosphere aged specimens emitted small amounts of carbon dioxide at the beginning of the mass loss. The activation energy for low degrees of conversion (<5%) increased in air and in nitrogen as a function of the conversion. For higher conversions a difference with progressing degradation emerged: in air, activation energies lowered continuously while they remained nearly constant under nitrogen.     

Application of TGA/DTA/MS to the Historic Preservation of Stone

The combined technique TGA/DTA/MS, thermogravimetric analysis/differential thermal analysis/mass spectrometry, has been used, in conjunction with other analytical techniques, FTIR, SEM, XRD, and optical microscopy, to analyze a specific patching material that had become seriously discolored on its surface after being used to repair a historic stone pillar at Bethesda Terrace in Central Park, New York in the 1980s. The stone patch was found to contain a polyacrylate binder which was associated with the discoloration.This revised version was published online in November 2005 with corrections to the Cover Date.     

Thermal and thermo-oxidative degradation of poly(hydroxy ether of bisphenol-A) studied by TGA/FTIR and TGA/MS

The nature and the extent of degradation of poly(hydroxy ether of bisphenol-A) phenoxy resin were analysed by thermogravimetry (TGA/DTGA) under nitrogen and air atmosphere. Decomposition kinetics were elucidated according to Flynn-Wall-Ozawa, Friedman and Kissinger methods. The evolved gases during degradation were inspected by a thermogravimetry analyser coupled with Fourier Transform Infrared Spectrometer (TGA/FTIR) and also with a TGA coupled to a Mass Spectrometer (TGA/MS). Mass spectra showed that chemical species evolved in phenoxy decomposition in air were very similar to those assigned from degradation in nitrogen (water, methane, CO, CO₂, phenol, acetone, etc.). However, these species appear in different amount and at different temperatures in both atmospheres. FTIR analysis of the evolved products showed that water and methane were the beginning decomposition products, indicating that decomposition is initiated by dehydration and cleavage of C-CH₃ bond in the bisphenol-A unit of phenoxy resin. After this initial stage, random chain scission is the main degradation pathway. Nevertheless, in air atmosphere, previously the complete decomposition of the phenoxy obtaining fundamentally CO₂, and water, the formation of an insulated surface layer of crosslinked structures has been proposed.     

Catalytic pyrolysis of waste wood chip over mesoporous materials using Py-GC/MS

Research on Chemical Intermediates - Pyrolysis Gas Chromatography/Mass Spectroscopy (Py-GC/MS) was used to investigate the catalytic pyrolysis of waste wood chip. Two different mesoporous...     

Combustion behaviour of some biodesulphurized coals assessed by TGA/DTA

Thermal analysis, i.e. TGA/DTA is used to study the changes in the combustion behaviour of microbially treated coals. In view of their high sulphur content and industrial significance three samples are under consideration, i.e. one lignite and two subbituminous from different region in Bulgaria. The differences in burning profiles can be related to structural changes resulted from biological treatments. The overall biological treatment generates these changes probably due to the oxidation process. Concerning organic sulphur biodesulphurization there is no change in any drastic manner of the thermal characteristic parameters. In general, applied biotreatments provoke a complex influence on combustion coal behaviour. From one side a better ignition performance, a minor decrease in higher heating value and diminishing peak temperature of maximum weight loss rate for all biotreated samples are observed. From other side some decrease in the combustibility indicated by an increase in the combustion time and the end of combustion temperature are obvious. Also well determined decrease of self-heating temperature after biotreatments evolves high risk of spontaneous unmanageable coal combustion.     

Dissipation and residue behaviour of oryzalin in grape ecosystem using RRLC-QqQ-MS/MS

The dissipation and terminal residues of oryzalin in grape ecosystem under open-field condition were investigated at two different locations, Beijing and Shandong in China. Residues in field-treated samples were determined by a sample method using rapid resolution liquid chromatography triples quadrupole tandem mass spectrometry (RRLC-QqQ-MS/MS). This method showed satisfactory qualitative and quantitative performance. The mean recoveries of oryzalin at different fortification levels (0.01, 0.1 and 1 mg/kg for grape; 0.01, 0.1, 1, 10 and 30 mg/kg for soil) ranged from 88.2% to 98.8%, with the relative standard deviations ≤4.9%. The limits of detection and quantification were, respectively, 0.003 and 0.01 mg/kg. In soil, the dissipation half-lives were about 9 days and the terminal residues ranged from <0.01 to 0.58 mg/kg in both Beijing and Shandong. The concentrations of oryzalin in grapes were lower than 0.01 mg/kg in most of the samples of dissipation study and all the samples of residue study. As far as we know, this is the first study focusing on the dissipation and terminal residue of oryzalin in grape ecosystem, and no maximum residue limits (MRLs) of oryzalin in grapes were recommended by China, Codex Alimentarius Commission or European Union . Therefore, these data not only provide important information about the fate and residues of oryzalin in grape ecosystem, but also could be very useful for the establishment of the MRLs of oryzalin in grapes.     

First report on the detection and quantification of arsenobetaine in extracts of marine algae using HPLC-ES-MS/MS

The detection of arsenobetaine in extracts of marine algae is reported here for the first time. The application of liquid chromatography coupled online with electrospray tandem mass spectrometry in the selected reaction monitoring mode provided improved performance for the detection of low amounts of arsenobetaine in the presence of high amounts of arsenosugars.     

Investigation of pyrolysis of chinese coals using thermal analysis/mass spectrometry

TA/MS (thermal analysis coupled with mass spectrometry) was applied to the pyrolysis of Chinese coals with different ranks. A total of 13 Chinese coals were investigated. The samples were deliberately chosen to represent the 13 types of Chinese coals according to the Chinese coal classification system. The experiments were carried out in an argon atmosphere with a flow rate of 150 ml min^-1. The samples were heated from 40 up to 1200°C with a constant heating rate of 10 k min^-1. The main evolved pyrolysis products were identified through the on-line recorded mass spectra. The thermal and evolution behavior was compared between the coals. The results showed a strong thermal and evaluation behavior dependence on the coal rank. Different aliphatic fragments and also some aromatic substances, which are of environmental concern (BTX, PAHs), were found to be released depending on the different types of coal. This revised version was published online in July 2006 with corrections to the Cover Date.     

General characteristics of the polysaccharides of brown algae

Summary From an acetonic extract of the roots ofFerula samarcandica Kor. have been isolated farnesiferol A, gummosin, and two new coumarin substances, samarcandin C₂₄H_30–32O₅ and samarcandone C₂₄H_28–30O₅. Samarcandin has been converted into samarcandone and their probable structures-I and II-have been established.Khimiya Prirodnykh Soedinenii, Vol. 4, No. 2, pp. 73–77, 1968     

General characteristics of the polysaccharides of brown algae

Conclusions It has been shown that the brown algae of the Sea of Japan contain, in addition to alginic acid, acid polysaccharides probably bound to a peptide component.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 2, pp. 73–76, 1969     

Influence of pyrolysis temperature and time on the cellulose fast pyrolysis products: Analytical Py-GC/MS study

Analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to achieve fast pyrolysis of cellulose and on-line analysis of the pyrolysis vapors. Experiments were performed to reveal the effects of pyrolysis temperature and time on the distribution of the pyrolytic products, especially the formation characteristics of eighteen important products. During the fast pyrolysis process, the cellulose started decomposition to form organic volatile products at the set pyrolysis temperature of 400 °C. The pyrolytic products included various anhydrosugars (dominated by the levoglucosan (LG)), anhydrosugar derivatives (mainly the levoglucosenone (LGO), 1,4:3,6-dianhydro-α-d-glucopyranose (DGP), 1,5-anhydro-4-deoxy-d-glycero-hex-1-en-3-ulose (APP) and 1-hydroxy-3,6-dioxabicyclo[3.2.1]octan-2-one (LAC)), furan compounds (typically the 5-hydroxymethyl-furfural (HMF), furfural (FF) and furan (F)), as well as light linear carbonyls (mainly the hydroxyacetaldehyde (HAA) and 1-hydroxy-2-propanone (HA)). These products were generated with different characteristics. The LG was the most important product, it was thermally stable, and its formation was favored at elevated pyrolysis temperature and time. Most of the other products were also enhanced at elevated pyrolytic conditions. However, some products, such as the LGO, were favorable to be produced at low temperatures. Based on these characteristics, discussion was performed on the possible pyrolytic pathways for the formation of the important products.     

2,6-Cyclo-xenicanes from the brown algae Dilophus fasciola and Dilophus spiralis

Seven new diterpenes, featuring the rare 2,6-cyclo-xenicane skeleton, along with eleven previously reported metabolites were isolated from the organic extracts of the brown algae Dilophus fasciola and Dilophus spiralis. The structure elucidation of the isolated natural products was based on detailed analyses of their spectroscopic data (NMR, MS, IR, UV), whereas the assignment of their relative configurations was assisted by molecular modelling studies.     

Analysis of siloxane pyrolysis products by cryo-GC/FT-IR and GC/MS

On line measurements of infrared and mass spectra of siloxane pyrolysis products separated by gas chromatography are described. The FT-IR absorbance spectra have been recorded from the eluates trapped as small spots on a moving window held at 77 K. Three of the main compounds separated were selected for FT-IR identification performed by comparing the spectra with GC/MS data and by spectral searching using a library of compounds measured under the same conditions.Dedicated to our most honourable teacher Professor Dr. H. Kriegsmann on the occasion of his 70th birthday