Mass spectrometry thermal analysis

In contrast to thermal ionization methods, where the tracer added must be of the same element as the analyte, tracers of different elemental composition but similar ionization efficiency can be utilized for inductively coupled plasma mass spectrometry (ICPMS) analysis. Hence, for ICPMS work, uranium can be added to thorium or radium samples as a way of correcting for instrumental mass bias (e g., Luo et al. 1997 Stirling et al. 2001 Pietruszka et al. 2002). The only drawback of this approach is that small inter-element (e g., U vs. Th) biases may be present during ionization or detection that need to be considered and evaluated (e.g., Pietruszka et al. 2002). 

Bromonitromethanes are substantially increased in formation with the use of pre-ozonation before chlorine or chloramine treatment, and concentrations up to 3 pg/L individually have been reported [11,12]. Laboratory-scale formation studies indicate that nitrite may play a role in the formation of the nitro group in these DBFs [40]. Tribromonitromethane (bromopicrin) and other trihalonitromethanes (which include bromodichloro- and chlorodibromonitromethane) require particular analytical conditions for their analysis. These compounds are thermally unstable and decompose under commonly used injection port temperatures during gas chromatography (GC) or GC/mass spectrometry (MS) analysis [41]. 

Gas Chromatography—Matrix Isolation Infrared Spectroscopy—Mass Spectrometry for Analysis of Thermally Generated Aroma Compounds... 

In recent years, several techniques have been developed for mass spectrometry, whereby samples are ionized and analysed from a condensed phase, without prior volatilization. These desorption techniques have permitted the extension of mass spectrometric analyses to sulfate and glutathione conjugates, as well as to underivatized and labile glucuronic acid conjugates. Primary among these techniques are field desorption 6, plasma desorption (7), laser desorption (8), fast atom bombardment (or secondary ion mass spectrometry with a liquid sample matrix) ( ) and thermospray ionization ( O). The latter can also serve to couple high pressure liquid chromatography and mass spectrometry for analysis of involatile and thermally labile samples. 

Mass spectrometry. Thermal treatments of the intercalated solids from room temperature to 1000 °C were carried out in quartz reactors under helium, with a flow rate of 3 cc/min. A Hidden Analytical HPR 20 Mass spectrometer (MS) was used for the analysis of the gases evolved upon thermal treatment, in the mass range 1-200 a.m.u. A capillary leak maintained at 170°C was used to divert a fraction of the gas flow to the analysis chamber. 

The method of analysis should be clearly stated and abbreviations such as MTA (mass-spectromelric thermal analysis) and MDTA (mass spectrometry and differential thermal analysis) avoided. 

Schnelle-Kreis, J. Welthagen, W. Sklorz, M. Zimmermann, R. (2005). Application of direct thermal desorption gas chromatography and comprehensive two-dimensional gas chromatography coupled to time of flight mass spectrometry for analysis of organic compounds in ambient aerosol particles. Journal of Separation Science, Vol.28, pp. 1648-1657, ISSN 1615-9314... 

These salts were characterized by IR, Raman and NMR spectroscopy, mass spectrometry, elemental analysis. X-ray, and initial safety testing (impact and friction sensitivity). Low impact sensitivities were demonstrated. Densities and thermochemical characteristics of substituted amino, amino-methyl, and polymethyl tetrazolium salts are summarized in Table 5. All of these new salts exhibit thermal stabilities > 170°C based on DSC/TGA studies (except the azide). The densities of l-amino-4,5-dimethyl tetrazolium perchlorate (45b) and l-methyl-4,5-diamino tetrazolium dinitramide (50b) are markedly higher than the others. 

Thermally decomposed TATB condensed phase products have been isolated by repeated thin layer chromatography (TLC) elution, and chemical ionization mass spectrometry (CIMS) analysis reveals at least three furoxan products formed by the loss of H2 and cyclization of adjacent amino and nitro groups (Figure 11). 3 This must involve N—H bond rupture and is consistent with it being the same... 

Thermo-molecular beam analysis Temperature modulated DSC cfr MTDSC) Thermomicrophotometry Thermo-optical analysis Thermo-oxidative degradation Time-of-flight laser-microprobe mass spectrometry Time-of-flight mass spectrometry Time-of-flight secondary ion mass spectrometry Thermal oxyluminescence Thermal programming Two-photon absorption spectroscopy... 

Thermal scanning microscopy Temperature-time profile Time/temperature resolved pyrolysis mass spectrometry Thermal ultraviolet Thermal volatilisation analysis Thermal wave infrared imaging Transmission X-ray microscopy Total-reflection X-ray fluorescence (c/r. TRXRF) Ultrasonic force microscopy Ultraviolet photoelectron spectroscopy Ultrasound... 

The methods discussed in this book are differential photocalorimetry, differential scanning calorimetry, dielectric thermal analysis, differential thermal analysis, dynamic mechanical analysis, evcrived gas analysis, gas chromatography, gas chromatography (oml)ined with mass spectrometry, mass spectrometry, microthermal analysis, thermal volalilisalion, Ihermogravimetric analysis and thermomechanical 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... 

The analysis of penicillins by mass spectrometry (qv) has developed with the advent of novel techniques such as fast atom bombardment. The use of soft ionization techniques has enabled the analysis of thermally labile nonvolatile compounds. These techniques have proven extremely valuable in providing abundant molecular weight information from underivatized penicillins, both as free acids and as metal salts (15). 

In addition to the main general methods of analysis outlined above there are also certain specialised techniques which are applied in special circumstances. Among these are X-ray methods, methods based upon the measurement of radioactivity, mass spectrometry, the so-called kinetic methods, and thermal methods. 

Thermogravimetric analysis has also been used in conjunction with other techniques, such as differential thermal analysis (DTA), gas chromatography, and mass spectrometry, for the study and characterisation of complex materials such as clays, soils and polymers.35... 

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-... 

H. Kramer, S. Semel J.E. Abel, Trace Elemental Survey Analysis of Trinitrotoluene , PATR 4767 (1975) (An evaluation of the applicability of spark source mass spectrometry and thermal neutron activation for the detn of origin-related trace elemental impurities in TNT) 10) C. Ribando J. Haber-man, Origin-Identification of Explosives Via Their Composite Impurity Profiles I. The... 

The combination of chromatography and mass spectrometry (MS) is a subject that has attracted much interest over the last forty years or so. The combination of gas chromatography (GC) with mass spectrometry (GC-MS) was first reported in 1958 and made available commercially in 1967. Since then, it has become increasingly utilized and is probably the most widely used hyphenated or tandem technique, as such combinations are often known. The acceptance of GC-MS as a routine technique has in no small part been due to the fact that interfaces have been available for both packed and capillary columns which allow the vast majority of compounds amenable to separation by gas chromatography to be transferred efficiently to the mass spectrometer. Compounds amenable to analysis by GC need to be both volatile, at the temperatures used to achieve separation, and thermally stable, i.e. the same requirements needed to produce mass spectra from an analyte using either electron (El) or chemical ionization (Cl) (see Chapter 3). In simple terms, therefore, virtually all compounds that pass through a GC column can be ionized and the full analytical capabilities of the mass spectrometer utilized. 

Haddon, W. E. and Harden, L. A., Advantages of particle beam sample introduction for analysis of thermally sensitive natural products by mass spectrometry , in Proceedings of the 39th ASMS Conference on Mass Spectrometry and Allied Topics, Nashville, TN, May 19-24, 1991, pp. 1316-1317. 

Thermal properties of several chlorinated phenols and derivatives were studied by differential thermal analysis and mass spectrometry and in bulk reactions. Conditions which might facilitate the formation of stable dioxins were emphasized. No two chlorinated phenols behaved alike. For a given compound the decomposition temperature and rate as well as the product distribution varied considerably with reaction conditions. The phenols themselves seem to pyro-lyze under equilibrium conditions slowly above 250°C. For their alkali salts the onset of decomposition is sharp and around 350°C. The reaction itself is exothermic. Preliminary results indicate that heavy ions such as cupric ion may decrease the decomposition temperature. 

The data in Table I are also significant in terms of the type of analysis to determine the presence of NDMA. In all cases analysis was done using gas chromatography coupled with a Thermal Energy Analyzer, a sensitive, relatively specific nitrosamine detector (12). Further, in six of the studies, the presence of NDMA in several samples was confirmed by gas chromatography-mass spectrometry (GC-MS). The mass spectral data firmly established the presence of NDMA in the beer samples. 

Reliable analytical methods are available for determination of many volatile nitrosamines at concentrations of 0.1 to 10 ppb in a variety of environmental and biological samples. Most methods employ distillation, extraction, an optional cleanup step, concentration, and final separation by gas chromatography (GC). Use of the highly specific Thermal Energy Analyzer (TEA) as a GC detector affords simplification of sample handling and cleanup without sacrifice of selectivity or sensitivity. Mass spectrometry (MS) is usually employed to confirm the identity of nitrosamines. Utilization of the mass spectrometer s capability to provide quantitative data affords additional confirmatory evidence and quantitative confirmation should be a required criterion of environmental sample analysis. Artifactual formation of nitrosamines continues to be a problem, especially at low levels (0.1 to 1 ppb), and precautions must be taken, such as addition of sulfamic acid or other nitrosation inhibitors. The efficacy of measures for prevention of artifactual nitrosamine formation should be evaluated in each type of sample examined. 

In a separate set of experiments designed to follow the gas phase reactions of CHj-radicals with NO, CHj- radicals were generated by the thermal decomposition of azomethane, CHjN NCHj, at 980 °C. The CH3- radicals were subsequently allowed to react with themselves and with NO in a Knudsen cell that has been described previously [12]. Analysis of intermediates and products was again done by mass spectrometry, using the VIEMS. Calibration of the mass spectrometer with respect to CH,- radicals was carried out by introducing the products of azomethane decomposition directly into the high vacuum region of the instrument. 

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