Spectrometric Thermal Analysis

Appel, B. R., S. M. Wall, and R. L. Knights, "Characterization of Carbonaceous Materials in Atmospheric Aerosols by High Resolution Mass Spectrometric Thermal Analysis, Adv. Environ. Sci. Technol., 10, 353-365 (1980). 

Shulman GP (1965) Thermal degradation of polymers I. Mass spectrometric thermal analysis. Polym Lett 3 911... 

For mass spectrometric thermal analysis (MTA), a method previously described (16), any ion intensity can be recorded as a function of sample temperature. This method has been developed on a time-of-flight mass spectrometer (12). A small sample is introduced into a miniaturized furnace located within the ion source structure as shown in Fig. 1 by... 

The Kiselev-Zhuravlev constant aoH value of 4.6 was obtained with a deuterium-exchange method that distinguished between surface and bulk OH and with a mass spectrometric thermal analysis (MTA) method in conjunction with temperature-programmed desorption (TPD) (66). 

Names rejected by the ICTA committee were effluent gas detection, effluent gas analysis, thermovaporimetric analysis, and thermohygrometric analysis. Also, terms such as mass spectrometric thermal analysis (MTA) and mass spectrometric differential thermal analysis (MDTA) should be avoided. Unfortunately, new names for the techniques are constantly being created, such as thermal evolution analysis (TEA). The technique of TEA, according to Chiu (18), includes all techniques that monitor continuously the amount of volatiles thermally evolved from the sample upon programmed heating. 

Appel, B. R. 1981. Characterization of carbonaceous materials in atmospheric aerosols by high-resolution mass spectrometric thermal analysis. In G. M. Hidy, ed.. The aerosol characterization experiment. Wiley-Interscience, New York. 

Table 9.4 Experimental details of mass spectrometric thermal analysis ...

In Table IX a distinction is made between mass spectrometric thermal analysis, in which the sample is actually located in the mass spectrometer, and mass spectrometry coupled to either DTA, TG, or both. The latter type is most often used by commercial instrument manufacturers. The... 

Mass spectrometric analysis Mass spectrometric thermal analysis Mass spectraneter coupled to DTA or TG... 

Alternative approaches consist in heat extraction by means of thermal analysis, thermal volatilisation and (laser) desorption techniques, or pyrolysis. In most cases mass spectrometric detection modes are used. Early MS work has focused on thermal desorption of the additives from the bulk polymer, followed by electron impact ionisation (El) [98,100], Cl [100,107] and field ionisation (FI) [100]. These methods are limited in that the polymer additives must be both stable and volatile at the higher temperatures, which is not always the case since many additives are thermally labile. More recently, soft ionisation methods have been applied to the analysis of additives from bulk polymeric material. These ionisation methods include FAB [100] and LD [97,108], which may provide qualitative information with minimal sample pretreatment. A comparison with FAB [97] has shown that LD Fourier transform ion cyclotron resonance (LD-FTTCR) is superior for polymer additive identification by giving less molecular ion fragmentation. While PyGC-MS is a much-used tool for the analysis of rubber compounds (both for the characterisation of the polymer and additives), as shown in Section 2.2, its usefulness for the in situ in-polymer additive analysis is equally acknowledged. 

Relatively few descriptions of direct mass spectral analysis of plastics compounds have appeared in the literature [22,37,63,240,243], Additives in PP were thermally desorbed into a heated reservoir inlet for 80 eV EI-MS analysis [240], Analysis of additives in PP compounds via direct thermal desorption ammonia CI-MS has been described [269] and direct mass spectrometric oligomer analysis has been reported [21],... 

Powdering, or grinding, of samples is a simple preparation method required in a number of spectrometric and spectroscopic techniques, such as x-ray diffraction (XRD), nuclear magnetic resonance (NMR), differential thermal analysis (DTA), thermogravimetric analysis (TG), or ATR-FTIR spectroscopy. Control of the particle size during grinding must be taken into account in attempting to obtain reliable results. 

Storms (1971) studied the phase relationship at temperatures between 1027 and 1827°C over a wide composition range in the Y-C system using a combination of mass spectrometric and thermal analysis techniques. Samples were prepared by arc melting purified crystal bar yttrium metal and a spectroscopically pure graphite rod. 

Thermal analysis of PS, poly-p-methylstyrene and polyalpha-methylstyrene was carried out using evolved-gas analysis by IR and mass spectrometry and direct-pyrolysis analysis by mass spectrometric techniques. Evolved-gas analysis, both by IR and mass spectrometry, revealed features due mainly to the corresponding monomers or stable, volatile and low relative molec.wt. degradation products. In direct-pyrolysis mass spectrometry, however, primary decomposition products and heavier fragments such as dimers and trimers could also be detected. The ion-temp, profiles of the corresponding monomer ions revealed information about the thermal stability of the polymers. 25 refs. (XXVIII Colloquium Spectroscopicum Internationale, York, UK, June/July 1993)... 

Anderson and Ereeman [11] studied the thermal properties of a styrenated polyester synthesised by condensation involving a glycol and two dicarboxylic acids, one of which was unsaturated. A crosslinking reaction of the styrene (used as a solvent and copolymer) was effected by the use of free-radical initiators. TGA, dynamic thermal analysis, IR and mass spectrometric techniques were used to study the thermal degradation of this polymer in air and in argon. Based upon IR analysis, the unit basic structure of the polyester was taken to be as in Equation 3.18 ... 

Particular emphasis has been placed on separation and spectrometric techniques in Sections D and E. Together with the electrochemical techniques of section C, they represent the major tools of the analytical chemist. Other special techniques, such as thermal analysis, may also be combined with them to reveal precise details of the processes occurring (see Topic G4). 

Spectrometric methods, especially mass sf>ectrometry (MS) and Fourier transform infrared spectrometry (FilR) have been used, often coupled with thermogravimetry. For molecules that are pwlar and of low molar mass, FTIR is particularly useful. For nonpwlar molecules and those of higher molar mass, MS is more adaptable. There are problems, however, in interfacing the thermal analysis instrument operating at atmospheric pressure to the MS operating imder vacuum. This is discussed in Topic F3. 

In EGA the gases evolved from the decomposition of materials in a thermal analysis unit are analyzed. There are many methods of analyzing gases. In the past, specific chemical methods have been favored, but now instrumental methods based largely on mass spectrometric methods, chromatography, or infrared spectroscopy are generally practiced. In certain applications, however, specific chemical analysis is still used. In thermal analysis there must be an interface between the heat-treated sample and the gas detection unit. Gas analysis is rarely used in such cases by itself but more commonly combined with TG or DTA. 

The reaction involves orthometallation of two aromatic rings with formation of two five-membered metallocycles. DTA/TG and mass-spectrometric analyses were performed to study the thermal process under a nitrogen atmosphere. In general, dehydrohalogenation reactions are not well suited to study by thermal analysis methods because evolution of corrosive hydrogen halides is deleterious to the equipment. 

To achieve sufficient vapor pressure for El and Cl, a nonvolatile liquid will have to be heated strongly, but this heating may lead to its thermal degradation. If thermal instability is a problem, then inlet/ionization systems need to be considered, since these do not require prevolatilization of the sample before mass spectrometric analysis. This problem has led to the development of inlet/ionization systems that can operate at atmospheric pressure and ambient temperatures. Successive developments have led to the introduction of techniques such as fast-atom bombardment (FAB), fast-ion bombardment (FIB), dynamic FAB, thermospray, plasmaspray, electrospray, and APCI. Only the last two techniques are in common use. Further aspects of liquids in their role as solvents for samples are considered below. 

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