GCMS Analysis

GCMS Analysis. The GCMS system utilized a Bendix model 2200 chromatograph connected to an AEI MS902 mass spectrometer, equipped with a high speed pumping system (9-Systems,... 

GCMS Analysis. High resolution MS may be used as the primary means for quantitative determination of nitrosamines (1, 11-13). Usually it is more convenient and efficient to use the TEA for this purpose and employ GCMS for confirmation of identity of nitrosamines tentatively identified by GC-TEA. 

Verzera, A., Campisi, S., Zappala, M., and Bonaccorsi, I. (2001). SPME-GCMS analysis of honey volatile components for the characterization of different floral origin. Am. Lab. 33, 18-21. 

E.R. de la Rie and S. Watts, GCMS analysis of terpenoid resins in situ derivatization procedures using quaternary ammonium hydroxides, Stud. Conserv., 47, 257 272 (2002). 

Concentration Methods. The GCMS analysis of an environmental sample starts with the isolation of the organic compounds from the matrix (air, water, food, etc.) into a form suitable for introduction into the GCMS instrument, typically a solution in a volatile solvent. This concentration step includes essentially three major methods vapor stripping, solvent extraction, and lipophilic adsorption. We have recently reviewed the detailed operation of these methods (Ij, (See also Bellar, Budde and Eichel-berger, this volume) but their general features will be outlined here. 

The identification of these 123 compounds (see Table I) was made possible only by the synergistic application of several analytical techniques. For example, the very high concentrations of a few compounds in most of the samples (e.g., no. 6,10,46, 81), precluded identification of many of the minor components during GCMS analysis. This dynamic range problem was solved, at least qualitatively, by HPLC followed by mass spectrometry. 

Structures of immobilized rhodium complexes on the sihca support have been proposed on the basis of the data obtained from C, P and Si MAS-NMR. NMR spectra of the rhodium-modified solid materials confirmed that trimethylsiloxide ligand was removed from the rhodium coordination sphere during the immobilization process. Formation of a new covalent bond between the rhodium organo-metallic moiety and the silica support occurs, probably with evolution of trimethylsilanol, which is rapidly converted into disiloxane (Me3Si)20. The presence of this molecule in the solution obtained after the silica surface modification process was confirmed by GCMS analysis. 

Dithiobispropionitrile was prepared as a reference standard for GCMS analysis according to the procedure of Johnston and Gallagher and was recrystallized from ether.2 Physical data for 3,3 -dithiobispropionitrile (unchecked) are as follows ... 

Ether solutions based on TAA salts are not reduced on noble metal electrodes. The major cathodic reaction of these solutions involves the cation reduction to trialkyl amine, alkane, and alkene (which are the stable disproportion products of the alkyl radical formed by the electron transfer to the cation) [3], Electrolysis of ethers such as THF or DME containing TBAP, formed in the catholyte tributyl amine, butane and butene, were unambiguously identified by NMR and GCMS analysis [3], In the presence of water (several hundred ppm and more), the electrolysis products were found to be tributyl amine and butene (butane was not detected) [3], The potential of this reduction reaction is higher than that of the dry solution, and it is clear that the initial electroactive species in this case is the... 

The checkers identified the two major impurities as p-bromophenyl vinyl sulfide (see Note 5) and 2-chloroethyl phenyl sulfide by GCMS analysis. 

Modem GCMS analysis and sample preparation techniques have overcome many the analytical problems associated with the investigation of organic sulfur compounds associated with potential reactions between elemental sulfur and organic matter during analysis (Hayes, 1967). Shimoyama and Katsumata (2001) examined the distribution of aromatic thiophenes in Murchison detecting benzothiophene, dibenzothiophene, alky-substituted dibenzothiophenes, and benzo-naphthothiophenes at concentrations levels of 0.3 ppm (Table 1) confirming earlier studies (Basile et al., 1984). 

Krinner G., Genthon C., and Jouzel J. (1997) GCM analysis of local influences on ice core S signals. Geophys. Res. Lett. 24, 2825-2828. 

Sewage sludge is known to contain a wide range of acidic and other polar compounds. Derivatisation was used to facilitate GC and GCMS analysis of these compounds in the more polar fractions from clean-up using Florisil and in some steam distillation extracts. The technique employed was methylation with diazomethane. 

Fig. 7.4 Major pyrolytic polycyclic aromatic hydrocarbon (PAH) distributions in Recent and ancient sediments, normalized to pyrene abundance (from molecular ion responses during GCMS analysis see Box 4.3 after Killops Massoud 1992). See Fig. 7.3 for key to names and structures.

Product percentages from GCMS analysis. Products listed in order of increasing retention time. 

After gas analysis, column cooled to -45 C for temperature programmed GCMS analysis of condensables from trap. 

Figure 5. - Thermal Desorption-GCMS Analysis of SOF From Diesel Particulates Compared With Diesel Lube Oil and Diesel Fuel...

Figure 4.1 shows a typical chromatogram from a GCMS analysis. The chromatogram, termed the total ion chromatogram (TIC), is reconstructed from a sum of all ion intensities for each individual mass spectrum. The x-axis represents time, in minutes, from the sample injection. 

There may be several hundred, or even thousand, mass spectra associated with a single GCMS analysis. Thus, a computerized system is required for collecting and reviewing the data. Such a system offers unlimited avenues for quickly evaluating the data for both qualitative (i.e., identification) and quantitative (compound concentration) purposes. 

FIGURE 4.1 Total ion chromatogram (TIC) from GCMS analysis. 

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