Field ionization mass spectrometry FIMS

FIMS Analysis. Selected extracts were sent for analysis by field ionization mass spectrometry (FIMS) at SRI International. This technique was described by St. 

Field ionization mass spectrometry (FIMS) was applied to the different compound classes by Boduszynski et al. (1980). The FIMS molecular weight envelopes shown in Fig. 8 illustrate the similar but wide molecular weight distribution for each compound class. Furthermore, the FIMS molecular weight of about 1000 are considerably lower than those obtained by other methods in which intermolecular association may influence measured values. This is evident in Table IX by the comparison of VPO... 

Mass Spectrometry. Electron impact (El) mass spectrometry was done at NRL on the effluent from a 6 ft. OV-101 packed GC column programmed from 70 to 210°C. Field ionization mass spectrometry (FIMS) was performed by SRI International on contract to NRL. In this latter analysis, the fuel sample was frozen on a solids inlet probe prior to insertion into the mass spectrometer. The spectra accumulated for each mass during a temperature program were normally totaled for data presentation (6). Molecules boiling below 140°C are lost or depleted with this technique but such compounds comprise a very small fraction of JP-5 or DFM. Since the ionization efficiency for hydrocarbon classes is currently under study, the FIMS data are utilized primarily in a qualitative sense. 

Field ionization mass spectrometry (FIMS) was initially developed for molecular weight determinations and mixture analyses. This soft ionization technique is particularly well suited for the mass spectrometric examination of the extremely complex mixture of compounds resulting from the pyrolysis of macromolecules because predominantly characteristic, high-mass molecular ions are produced. ... 

Pyrolysis-field ionization mass spectrometry (Py-FIMS) and Curie-point pyrolysis-gas chromatography/mass spectrometry (CpPy-CC/MS) of soils... 

Seven Argonne Premium coal samples ranging from lignite to low volatile bituminous in rank were analyzed by Pyrolysis-Field Ionization Mass Spectrometry (Py-FIMS) in order to determine the existence and structural nature of a thermally extractable "mobile phase". In addition, Curie-point Pyrolysis-Low Voltage Mass Spectrometry (Py-LVMS) was employed to demonstrate the importance of mild oxidation on the thermally extractable mobile phase components. 

Analytical pyrolysis with field ionization mass spectrometry (online Py-FIMS) or in combination with GC/MS (Curie point Py-GC/MS) led to a significant increased number of identified subunits (e.g., Bracewell et al., 1989 Schulten et al., 2002). In addition, the application of tetramethylammonium hydroxide (TMAH) methylation, followed by GC/MS, was successfully applied. The most abundant pyrolysis products identified are benzene, phenol and furan derivatives, aliphatic and carboxylic compounds, and indene derivatives (Schulten et al.,2002). New approaches have been used for the quantification of n-alkyl fatty acids of DOM and isolated fractions in the form of individual compounds after solvent extraction followed by derivatiza-tion with TMAH. 

Analytical pyrolysis is defined as the characterization of a material or a chemical process by the instrumental analysis of its pyrolysis products (Ericsson and Lattimer, 1989). The most important analytical pyrolysis methods widely applied to environmental samples are Curie-point (flash) pyrolysis combined with electron impact (El) ionization gas chromatography/mass spectrometry (Cp Py-GC/MS) and pyrolysis-field ionization mass spectrometry (Py-FIMS). In contrast to the fragmenting El ionization, soft ionization methods, such as field ionization (FI) and field desorption (FD) each in combination with MS, result in the formation of molecule ions either without, or with only very low, fragmentation (Lehmann and Schulten, 1976 Schulten, 1987 Schulten and Leinweber, 1996 Schulten et al., 1998). The molecule ions are potentially similar to the original sample, which makes these methods particularly suitable to the investigation of complex environmental samples of unknown composition. 

Figure 14.5. Fatty acids patterns of soils under long-term monoculture, (a) Lipid extract of soil under maize, unfertilized, after derivatization with tetramethylammonium hydroxide determined by conventional gas chromatography/mass spectrometry (GC/MS) in comparison to direct, in-source pyrolysis-field ionization mass spectrometry (Py-FIMS) without derivatization (Jandl et al., unpublished), (b) Py-FIMS of lipid extract of soil under rye, farmyard manure (FYM) treatment, compared to solid extraction residue, both directly measured without derivatization. Reprinted from Marschner, B., Brodowski, S., Dreves, A., et al. (2008). How relevant is recalcitrance for the stabilization of organic matter in soils Journal of Plant Nutrition and Soil Science 171, 91-110, with permission from Wiley-VCH.

FIMS Fingerprint. Field ionization mass spectrometry of a mixture affords a spectrum of the molecular ions since fragmentation is minimal. Thus a distribution of molecular sizes and hydrocarbon classes can be obtained from a single analysis. This is illustrated in Figure 1 which compares the FIMS fingerprints for JP-5 from Shale-I and Shale-II refining. Distinct differences can be noted. The preponderance of alkanes (C... 

Mass Spectrometry of LC Fractions. The fractions from the preparative scale LC were subjected to GC/MS analysis with electron impact ionization. The total fractions were also analyzed by field ionization mass spectrometry with a direct insertion probe. The FIMS m/e plot for DFM fraction five is depicted in Figure 3. 

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