Changes

==Internal standards==

==Internal standards==

[[file:oiloil-and-oilsource-rock-correlations_fig8-43.png|300px|thumb|{{figure number|4}}See text for explanation.]]

[[file:oiloil-and-oilsource-rock-correlations_fig8-43.png|300px|thumb|{{figure number|4}}m/z 191 (top) and 217 (bottom) mass chromatograms for a seep oil from Papua New Guinea.]]

Internal standards can appear in GC/MS data as well as in gas chromatograms. [[:file:oiloil-and-oilsource-rock-correlations_fig8-43.png|Figure 4]] shows m/z 191 (top) and 217 (bottom) mass chromatograms for a seep oil from Papua New Guinea. The three peaks in the top chromatogram to the left of T_s come from the internal standard, which was supposed to be a single compound but is actually a mixture (probably of various isomers of the same compound). The internal standard was unlabelled on this mass chromatogram and, as such, poses a serious risk even for experienced interpreters since the internal standard peaks might be thought to represent indigenous compounds.

Internal standards can appear in GC/MS data as well as in gas chromatograms. [[:file:oiloil-and-oilsource-rock-correlations_fig8-43.png|Figure 4]] shows m/z 191 (top) and 217 (bottom) mass chromatograms for a seep oil from Papua New Guinea. The three peaks in the top chromatogram to the left of T_s come from the internal standard, which was supposed to be a single compound but is actually a mixture (probably of various isomers of the same compound). The internal standard was unlabelled on this mass chromatogram and, as such, poses a serious risk even for experienced interpreters since the internal standard peaks might be thought to represent indigenous compounds.