Pyrolysis high-resolution mass spectrometry

The pyrolysis high resolution mass spectrometry (PyHRMS) technique has been described in detail previously (20). Briefly, the coal sample was placed on a platinum rhodium mesh on the end of a probe as a slurry. After the solvent had evaporated, the probe was inserted into the mass spectrometer and positioned within 5 mm of the source. The probe, which had been previously calibrated with an infra-red thermometer, was computer-controlled to give a temperature profile beginning at 100°C and increasing at 50°C/min to 800 C. The precise masses were matched to their corresponding chemical structures by computer programs developed in-house. This technique results in the relatively slow vacuum pyrolysis of the coal sample. 

Figure 7. Comparison of inverse gas chromatography and pyrolysis high resolution mass spectrometry experiments for Pochontas lv bituminous coal.

P. Miketova, C. Abbas-Hawks, K.J. Voorhees, and T.L. Hadfield, Microorganism Gram-type differentiation of whole cells based on pyrolysis-high resolution mass spectrometry data, J. Anal. Appl. Pyrolysis, 67 109 (2003). 

Pouwels, A.D. Eijkel, G.B. Boon, J.J. Curie-point pyrolysis-capillary gas chromatography-high resolution mass spectrometry of microcrystalline cellulose. J. Anal. Appl. Pyrolysis 1989, 14, 237-280. 

Boon, J.J. and J.W. De Leeuv, Amino acid sequence information in proteins and complex proteinaceous material revealed by pyrolysis-capUlary gas chromatography low and high resolution mass spectrometry,/. Ana/. App/. Pyrol, 11 313-327 (1987). Mariner, W.N. and P. Magidman, Analysis of wool proteins by pyrolysis-gas chromatography, in Preprints of 198th ACS National Meeting, Miami, Florida, September 1989. 

Figure 2. Weight loss during the pyrolysis of oxygen cured fibers derived from PCSZ, In a flow of argon (P = 100 kPa Q = 1/hour ). The inset shows the gas evolution by high resolution mass spectrometry from a fiber pre-pyrolyzed at 1200 C under argon [10] reproduced with permission.

Evidence for fluorenone (12) as a minor product of the pyrolysis (a small peak at mass 180 that persisted at reduced ionizing voltage) was indeed found. Direct-coupled gas chromatography-mass spectrometry clearly identified a minor component as fluorenone and a precise mass-measurement on a high-resolution mass spectrometer established C13H80+ as the empirical formula of the major component of nominal mass 180. 

Scheijen, M.A., J.J. Boon, W. Hass, and V. Heemaim Characterization of tobacco hgnin preparations by Curie-point pyrolysis-mass spectrometry and Curie-point pyrolysis-high resolution gas chromatography/ mass spectrometry J. Anal. Appl. Pyrolysis 15 (1989) 97-120. 

While the chemiluminescence detectors have considerable selectivity for nitrosamines it must also be recognized that the possibility exists that any compound that can produce NO during pyrolysis will produce a signal (20). For example, TEA responses have been observed from organic nitrites, C-nitro and C-nitroso compounds (17,28) and nitramines (29). In the routine analysis of N-nitroso compounds, possible TEA analyzer responses to compounds other than N-nitroso derivatives normally do not represent a problem since the the identity of a compound can be readily established by co-elution with known standards on GC-TEA and/or HPLC-TEA systems (30-34). Additional confirmation could be provided when the sample can be chromatographed on both GC-TEA and HPLC-TEA (30,33). The technique accepted as the most reliable for the confirmation of N-nitrosamines is based on mass spectrometry (22, 35,36). Low-resolution mass spectrometry is satisfactory for the analysis of relatively simple mixtures and in those instances in which extensive clean-up of samples has been performed. However, complex samples require more sophisticated GC and MS procedures (e.g., high resolution-MS). 

VAN DE Meent D., Brown S. C., Philp R. P. and Simoneit B. R. T. (1980) Pyrolysis-high resolution gas chromatography and pyrolysis-gas chromatography/mass spectrometry of kerogens and kerogen precursors. Geochim. Cosmochim. Acta 44, 999-1013. 

Ruff, C., K. Hor, B. Weckerle, and R Schreier, 2000. H/ H ratio analysis of flavor compounds by on-line gas chromatography pyrolysis isotope ratio mass spectrometry (HRGC-P-IRMS) Benzaldehyde. J. High Resolut. Chromatogr., 23 357-359. 

GC = gas chromatography, Py = pyrolysis (flash or hydrous heating), MS = mass spectrometry (HR = high resolution), IRMS = isotope ratio mass spectrometry, HPLC = high-pressure liquid chromatography, EC = electron capture. Cl = chemical ionization, NMR = nuclear magnetic resonance spectrometry. X-ray = X-ray crystallography. 

Li X, Lv P, Wang L, Guo A, Ma M, Qi X. Application of high resolution pyrolysis gas chromatog-raphy/mass spectrometry (HRPGC/MS) for detecting Listeria monocytogenes. J ChromatogrB Anal Technol Biomed Life Sci. 2014 971 107-11. doi 10.1016/j.jchromb.2014.06.032. 

Understanding the relationship between the molecular structure and the thermal stability (decomposition temperature and rate) of the organoclays and the subsequent influence on the stability of the polymer host is critical. Several analytical techniques have been used to determine the thermal stability of different organoclays and to indentify the decomposition products conventional and high-resolution thennogravimetric analysis (TGA) coupled with Fourier transform infrared spectroscopy (FITR) and mass spectrometry (MS), pyrolysis/gas chromatography (GC)-MS, and solid phase microextraction (SPME) [6-12]. 

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