Simultaneous thermal analysis-mass spectrometry

Continuous monitoring of the carbon monoxide and carbon dioxide evolved during thermal decomposition of brominated polyester resin samples, has been carried out using a simultaneous thermal analysis-mass spectrometry technique. In order to allow measurement of the carbon monoxide evolved, the atmosphere chosen for these runs was 21% oxygen in argon, since the peak at 28 atomic mass units (amu)... 

Lopez-Capel, E., Bol, R., and Manning, D. A. C. (2005a). Application of simultaneous thermal analysis mass spectrometry and stable carbon isotope analysis in a carbon sequestration study. Rapid Comm. Mass. Spect. 19, 3192-3198. 

Sample analysis by thermal ionization mass spectrometry (TIMS) results in measurement of isotopic ratios of minerals. Total mineral content of samples is then determined by one of two methods. One approach is to use flame atomic absorption spectrophotometry (AAS) to determine total mineral content of samples. Since AAS does not have the same level of precision as TIMS a sufficient number of replicates is analyzed for a mineral content determination with a CV of within 1%. Alternatively if a mineral has 3 or more isotopes and fractionation corrections are not made the following procedure may be used. An individual is fed one isotope and another isotope is added to the sample prior to analysis to determine the total mineral content of the sample by dilution of the second isotope. In this way both the amount of the isotope fed which is recovered in the feces and the total mineral content of the sample can be determined simultaneously. If fractionation corrections are to be made a mineral must have at least four isotopes. Details of these procedures will be reported separately. 

Simultaneous Thermal Analysis (STA) and Mass Spectrometry Systems) The Fine Work Co. Ltd... 

Yuen HK, Mappes GW, Grote WA. An automated system for simultaneous thermal analysis and mass spectrometry. Thermochim Acta. 1982 52 143-53. 

A two-step degradation mechanism for pofycaprolactone has been proposed by Persenaire et al. [42], They studied thermal degradation of PCL by high resolution thermogravimetric analysis (TGA) simultaneously coupled with mass spectrometry (MS) arrd Forrrier transform infrared spectrometry (FTIR). Based on evolved gas analysis by both MS and FTIR it was concluded that the first step was a random rupture of polyester chains via cw-elimination reaction which produced H2O, CO2, and 5-hexanoic acid. The second step is an unzipping depolymerization process at the chain ends with hydroxyl end groups to form e-caprolactone (see Fig. 4.2). 

The other practice of thermal analysis in which more than one technique is used is coupled simultaneous techniques. This term covers the application of two or more techniques to the same sample when the two instruments involved are connected by an interface, for example, simultaneous DTA and mass spectrometry. The term interface refers to a specific piece of equipment that enables the two instruments to be joined together. In coupled simultaneous techniques as in discountinuous simultaneous techniques, the first technique mentioned refers to the first in time measurement. Thus, when a DTA instrument and a mass spectrometer are used together, then DTA-MS is correct. 

His researches and those of his pupils led to his formulation in the twenties of the concept of active catalytic centers and the heterogeneity of catalytic and adsorptive surfaces. His catalytic studies were supplemented by researches carried out simultaneously on kinetics of homogeneous gas reactions and photochemistry. The thirties saw Hugh Taylor utilizing more and more of the techniques developed by physicists. Thermal conductivity for ortho-para hydrogen analysis resulted in his use of these species for surface characterization. The discovery of deuterium prompted him to set up production of this isotope by electrolysis on a large scale of several cubic centimeters. This gave him and others a supply of this valuable tracer for catalytic studies. For analysis he invoked not only thermal conductivity, but infrared spectroscopy and mass spectrometry. To ex-... 

The thermal characterisation of elastomers has recently been reviewed by Sircar [28] from which it appears that DSC followed by TG/DTG are the most popular thermal analysis techniques for elastomer applications. The TG/differential thermal gravimetry (DTG) method remains the method of choice for compositional analysis of uncured and cured elastomer compounds. Sircar s comprehensive review [28] was based on single thermal methods (TG, DSC, differential thermal analysis (DTA), thermomechanical analysis (TMA), DMA) and excluded combined (TG-DSC, TG-DTA) and simultaneous (TG-fourier transform infrared (TG-FTIR), TG-mass spectroscopy (TG-MS)) techniques. In this chapter the emphasis is on those multiple and hyphenated thermogravimetric analysis techniques which have had an impact on the characterisation of elastomers. The review is based mainly on Chemical Abstracts records corresponding to the keywords elastomers, thermogravimetry, differential scanning calorimetry, differential thermal analysis, infrared and mass spectrometry over the period 1979-1999. Table 1.1 contains the references to the various combined techniques. 

During investigation of a new material it is unlikely that any single thermal analysis technique will provide all the information required to understand its behavior. Complementary information is usually needed, which may be from another simultaneous thermal technique such as thermogravimetric-differential scanning calorimetric-mass spectrometry (TG-DSC-MS), gas chromatography (TG-GC, or DSG-GG), or spectroscopic methods such as IR spectroscopy or X-ray photoelectron spectroscopy (XPS). 

TGA experiments on polymeric systems often show complex TGA mass/temperature curves in which multiple decomposition products correspond with the weight change observed (see, for example, Figure 2.10). TGA has thus proven to be an excellent quantitative technique but less suitable for specification. This drawback can be eliminated if the components which are causing the mass losses detected, are also analysed simultaneously, the so-called evolved gas analysis (EGA). Several TGA-EGA systems are described in literature, analysing the evolved gases with different techniques i.e. thermal conductivity, cold-trapping followed by GC, mass spectrometry (MS) and infrared (FTIR). MS and FTIR have proven to be the most powerful techniques [3, 10]. 

Shepherd Chenery (1995) pioneered the laser ablation ICP-MS (inductively coupled plasma-mass spectrometry) method of analyzing individual fluid inclusions. An UV laser ablation microprobe is used to drill a hole into a mineral, to reach an inclusion up to 60/zm below the sample surface. For the laser ablation procedure the sample is placed in a modified thermal vacuum cell. The elevated temperature in the ablation cell raises the internal vapor pressure of the inclusion, which causes instantaneous rupture and highly efficient fluid expulsion as the beam breaches the inclusion wall. The vacuum pulls the vaporized fluid into the ICP-MS, where it is analyzed for major and minor ion concentrations. The advantages of the ICP-MS method are the small spot size of the laser (<2 m), allows analysis of small inclusions (> 10/zm) in a variety of minerals (halite, calcite, quartz, and others). A wide range of ions can be analyzed simultaneously, including low concentrations of minor ions. With multicollector ICP-MS, it will be possible to analyze strontium isotopes and other stable isotopes (5 C, S 0, S S) in fluid inclusions. Laser ablation ICP-MS is not as precise as other methods ( 30%) and the results can only be reported as ionic ratios as the volume of an inclusion cannot be determined prior to analysis. However, if the concentration... 

In the past several years, a number of new ionization methods in mass spectrometry have been introduced. These new techniques have extended mass spectrometric analysis to a wide variety of labile (thermally unstable), highly polar, and higher molecular weight materials. Field ionization (FI) and field desorption (FD) are two of the pioneering techniques in this list of alternative ionization methods. FI-MS, which was introduced for organic molecules in 1954, was the first soft ionization method. (Soft ionization refers to processes that produce high relative abundances of molecular, or quasimolecular, ions.) FD-MS, which was invented in 1969, was the first desorption/ionization method. (Desorption/ionization refers to processes in which die vaporization/ desorption, and ionization steps occur essentially simultaneously.)... 

Although water is known as a natural plasticizer for many polar polymers such as nylon, polyester resins, and cellulosic polymers, similar behavior for polyacrylamide and poly(acrylamide-co-acrylic acid) has not been investigated. In this study, the effect of water content (and/or thermal history) on the Tg s of acrylamide-based pol3 TOers was studied by Differential Scanning Calorimetry (DSC), Thermogravimetry (TG), Thermomechanical Analysis (TMA), and Simultaneous Thermogravimetry - Mass Spectrometry (TG/MS). 

The thermal behaviour of Tio,75(OH)i 5F1 5 was evaluated by simultaneously coupled thermogravimetric and mass spectrometry analysis (TGA-MS). 

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