Changes

  | part    = Critical elements of the petroleum system

  | part    = Critical elements of the petroleum system

  | chapter = Oil–oil and oil–source rock correlations

  | chapter = Oil–oil and oil–source rock correlations

  | frompg  = 8-1

  | frompg  = 8-30

  | topg    = 8-71

  | topg    = 8-32

  | author  = Douglas W. Waples, Joseph A. Curiale

  | author  = Douglas W. Waples, Joseph A. Curiale

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch08/ch08.htm

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch08/ch08.htm

  | isbn    = 0-89181-602-X

  | isbn    = 0-89181-602-X

}}

}}

GC/MS is a technique used to identify and quantify those compounds present in small concentrations that cannot be adequately separated, identified, and quantified using gas chromatography

 

GC/MS is a technique used to identify and quantify those compounds present in small concentrations that cannot be adequately separated, identified, and quantified using [[gas chromatography]].

==Selected ion monitoring (SIM)==

==Selected ion monitoring (SIM)==

==Example of SIM==

==Example of SIM==

[[file:oiloil-and-oilsource-rock-correlations_fig8-21.png|thumb|{{figure number|1}}. Copyright: Unocal.]]

[[file:oiloil-and-oilsource-rock-correlations_fig8-21.png|thumb|300px|{{figure number|1}}Three SIM mass chromatograms for a single oil sample. (top left) m/z 191 chromatogram; (bottom left) m/z 217 fragment in the mass spectrometer; (top right) m/z 218 fragment. Copyright: Unocal.]]

[[:file:oiloil-and-oilsource-rock-correlations_fig8-21.png|Figure 1]] shows three SIM mass chromatograms for a single oil sample. The top left chromatogram show the m/z 191 chromatogram, in which the only compounds are those having a fragment ion with a mass of 191 daltons. (The value m/z is the mass of the ion divided by its charge.) The bottom left chromatogram shows the compounds yielding an m/z 217 fragment in the mass spectrometer, while the top right chromatogram shows those compounds that give an m/z 218 fragment. The 217 and 218 mass chromatograms are very similar because both are derived mainly from steranes. The differences in relative intensity reflect the tendency of some types of steranes to give more 217 daughter ions and others to give more 218. These tendencies are due to structural differences among different families of steranes and are useful in themselves.

[[:file:oiloil-and-oilsource-rock-correlations_fig8-21.png|Figure 1]] shows three SIM mass chromatograms for a single oil sample. The top left chromatogram show the m/z 191 chromatogram, in which the only compounds are those having a fragment ion with a mass of 191 daltons. (The value m/z is the mass of the ion divided by its charge.) The bottom left chromatogram shows the compounds yielding an m/z 217 fragment in the mass spectrometer, while the top right chromatogram shows those compounds that give an m/z 218 fragment. The 217 and 218 mass chromatograms are very similar because both are derived mainly from steranes. The differences in relative intensity reflect the tendency of some types of steranes to give more 217 daughter ions and others to give more 218. These tendencies are due to structural differences among different families of steranes and are useful in themselves.

==Example of MRM==

==Example of MRM==

[[file:oiloil-and-oilsource-rock-correlations_fig8-22.png|thumb|{{figure number|2}}. Copyright: Murray et al. (1993); courtesy Australian Geological Survey Organization.]]

[[file:oiloil-and-oilsource-rock-correlations_fig8-22.png|300px|thumb|{{figure number|2}}MRM output for steranes from the Lufa oil seep in Papua New Guinea. Copyright: Murray et al.;<ref name=Maurray1993>Murray, A. P., R. E. Summons, J. Bradshaw, and B. Pawih, 1993, Cenozoic oil in Papua New Guinea—evidence from geochemical analysis of two newly discovered seeps, in G. J. Carman and Z. Carman, eds., Petroleum Exploration and Development in Papua New Guinea: Proceedings of the Second PNG Petroleum Convention, Australian Geological Survey, p. 489–498.</ref> courtesy Australian Geological Survey Organization.]]

[[:file:oiloil-and-oilsource-rock-correlations_fig8-22.png|Figure 2]] shows MRM output for steranes from the Lufa oil seep in Papua New Guinea. The same sample was also discussed in [[Data obtained by gas chromatography]]. Each fragmentogram monitors the transformation of a particular molecular ion to the designated daughter ion. The top four traces monitor conversion to the m/z 217 fragment ion from four different sizes of original sterane molecules. The top chromatogram represents the decomposition of methylsteranes (molecular weight = 414 daltons), and through its very low relative intensity at 100% scale (1.7) shows these compounds to be present in minor amounts. The next three chromatograms are for the C₂₉, C₂₈, and C₂₇ steranes, respectively. From the relative concentrations (24.4, 10.6, and 15.8) of these fragments, we see the C₂₉ species is dominant. The fifth chromatogram monitors 4-methylsteranes, which in this sample represent only minor components. The last two fragmentograms, in contrast, monitor two different bicadinane species.

[[:file:oiloil-and-oilsource-rock-correlations_fig8-22.png|Figure 2]] shows MRM output for steranes from the Lufa oil seep in Papua New Guinea. The same sample was also discussed in [[Data obtained by gas chromatography]]. Each fragmentogram monitors the transformation of a particular molecular ion to the designated daughter ion. The top four traces monitor conversion to the m/z 217 fragment ion from four different sizes of original sterane molecules. The top chromatogram represents the decomposition of methylsteranes (molecular weight = 414 daltons), and through its very low relative intensity at 100% scale (1.7) shows these compounds to be present in minor amounts. The next three chromatograms are for the C₂₉, C₂₈, and C₂₇ steranes, respectively. From the relative concentrations (24.4, 10.6, and 15.8) of these fragments, we see the C₂₉ species is dominant. The fifth chromatogram monitors 4-methylsteranes, which in this sample represent only minor components. The last two fragmentograms, in contrast, monitor two different bicadinane species.

==See also==

==See also==

* [[Molecular parameter data]]

* [[Molecular parameter data for oil–oil and oil–source rock correlations]]

* [[Data obtained by gas chromatography]]

* [[Gas chromatography: data obtained]]

* [[Environments indicated by specific compounds]]

* [[Organic compounds: environmental indicators]]

* [[Examples of correlations using GC/MS]]

* [[Gas chromatography/mass spectrometry (GC/MS): examples of correlations]]

* [[Limitations of GC/MS]]

* [[Gas chromatography/mass spectrometry (GC/MS): limitations]]

* [[High-performance liquid chromatography]]

* [[High-performance liquid chromatography]]

==External links==

==External links==

[[Category:Critical elements of the petroleum system]]  

[[Category:Critical elements of the petroleum system]]  

[[Category:Oil–oil and oil–source rock correlations]]

[[Category:Oil–oil and oil–source rock correlations]]