Gas chromatography/electron ionization

E.M. Jakubowski, C.L. Woodard, M.M. Mershon and T.W. Dolzine, Quantification of thiodiglycol in urine by electron ionization gas chromatography-mass spectrometry, J. Chromatogr., 528, 184-190 (1990). 

Jakubowski EM, Woodard CL, Mershon NM, Dolzine TW. 1990. Quantitation of thiodiglycolin urine by electron ionization gas chromatography-mass spectrometry. Journal of Chromatography 528 184-190. 

Wilson, R.T. Groneck, J.M. Holland, K.P. Henry, A.C. Determination of clenbuterol in cattle, sheep, and swine tissues by electron ionization gas chromatography-miass spectrometry. J. AOAC Int. 1994, 77, 917-924. 

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. 

G.S. Baird, R.L. Fitzgerald, S.K. Aggarwal and D.A. Herold, Determination of blood lead by electron-capture negative chemical ionization gas chromatography-mass spectrometry. Clin. Chem. 42, 286-291 (1996). 

Trichothecene mycotoxins are secondary metabolites of various fungal species. Structures of some trichothecene mycotoxins of interest to the US ARMY are given in Figure 1. Several methods have been reported for the analysis of these toxins (1-11, 15). Of these, mass spectrometry techniques are both sensitive and definitive when applied to toxicologic and environmental samples. With current technology, the most sensitive and qualitatively definitive analytical technique for the determination of these toxins is derivatization with an electron deficient moiety followed by analysis with negative ion chemical ionization gas chromatography-mass spectrometry (NICI-GC/HS). 

Melchert, H.-U. Pabel, E (2004). Reliable identification and quantification of trichothecenes and other mycotoxins by electron impact and chemical ionization-gas chromatography-mass spectrometry, using an ion-trap system in the multiple mass spectrometry mode. Candidate reference method for complex matrices. Journal of Chromatography A, Vol. 1056, No. 1-2, (November 2004), 195-199, ISSN 0021-9673. 

Environmental Analysis One of the most important environmental applications of gas chromatography is for the analysis of numerous organic pollutants in air, water, and wastewater. The analysis of volatile organics in drinking water, for example, is accomplished by a purge and trap, followed by their separation on a capillary column with a nonpolar stationary phase. A flame ionization, electron capture, or... 

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. 

The primary method for detecting methyl parathion and metabolites in biological tissues is gas chromatography (GC) coupled with electron capture (BCD), flame photometric (FPD), or flame ionization detection (FID). Sample preparation for methyl parathion analysis routinely involves extraction with an organic solvent (e g., acetone or benzene), centrifugation, concentration, and re suspension in a suitable solvent prior to GC analysis. For low concentrations of methyl parathion, further cleanup procedures, such as column chromatography on silica gel or Florisil are required. 

ECD = electron capture detector GC = gas chromatography HPLC = high-performance liquid chromatography MC = microcoulometric detector MS = mass spectrometry NICI = negative ion chemical ionization RSD = relative standard deviation SPE = solid phase extraction... 

This technique detects substances qualitatively and quantitatively. The chromatogram retention time is compound-specific, and peak-height indicates the concentration of pollutant in the air. Detection systems include flame ionization, thermal conductivity and electron capture. Traditionally gas chromatography is a laboratory analysis but portable versions are now available for field work. Table 9.4 lists conditions for one such portable device. 

ECD = electron capture detector FID = flame ionization detection GC = gas chromatography HECD = Hall electrolytic conductivity detector HRGC = high-resolution gas chromatography HSD = halogen-specific detector H2SO4 = sulfuric acid MS = mass spectrometry NR = not reported PID = photoionization detection UV = ultraviolet detection... 

J.J. Jimenez, J.L. Bernal, S. Aumente, M.J. delNozal, M.T. Martin, J. Bernal, Quality assurance of commercial beeswax I. Gas chromatography electron impact ionization mass spectrometry of hydrocarbons and monoesters, Journal of Chromatography A, 1024, 147 154 (2004). 

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