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Line 105: − + − [[file:oiloil-and-oilsource-rock-correlations_fig8-17.png|left|thumb|{{figure number|13}}Gas chromatograms of the saturated hydrocarbons from two seep oils from Papua New Guinea.]]+ + + − − [[file:oiloil-and-oilsource-rock-correlations_fig8-18.png|thumb|{{figure number|14}}Gas chromatogram of the saturated hydrocarbons from the Lufa seep oil, another seep oil from Papua New Guinea. Copyright: Murray et al.;<ref name=Murray>Murray, A. P., R. E. Summons, J. Bradshaw, and B. Pawih, 1993, Cenozoic Ooil in Paua 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.]]
Gas chromatography: data obtained (view source)
Revision as of 13:23, 21 May 2014
, 13:23, 21 May 2014→Limitations due to internal standards
==Limitations due to internal standards==
==Limitations due to internal standards==
<gallery mode=packed heights=300px widths=300px>
file:oiloil-and-oilsource-rock-correlations_fig8-17.png|{{figure number|13}}Gas chromatograms of the saturated hydrocarbons from two seep oils from Papua New Guinea.
file:oiloil-and-oilsource-rock-correlations_fig8-18.png|{{figure number|14}}Gas chromatogram of the saturated hydrocarbons from the Lufa seep oil, another seep oil from Papua New Guinea. Copyright: Murray et al.;<ref name=Murray>Murray, A. P., R. E. Summons, J. Bradshaw, and B. Pawih, 1993, Cenozoic Ooil in Paua 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.
</gallery>
An internal standard is commonly coinjected with the sample to aid in quantification during gas chromatography. If this internal standard is not clearly labeled on the chromatogram, it may be confused with an indigenous compound and erroneously used in correlation.
An internal standard is commonly coinjected with the sample to aid in quantification during gas chromatography. If this internal standard is not clearly labeled on the chromatogram, it may be confused with an indigenous compound and erroneously used in correlation.
===Examples of problems with internal standards===
===Examples of problems with internal standards===
[[:file:oiloil-and-oilsource-rock-correlations_fig8-17.png|Figure 13]] shows gas chromatograms of the saturated hydrocarbons from two seep oils from Papua New Guinea. Both samples contain an internal standard that elutes just before ''n''-C<sub>21</sub>. Because the left oil is biodegraded, the detector sensitivity was set very high to record the trace amounts of remaining ''n''-alkanes. Consequently, the internal standard peak is very tall. In contrast, the right oil (undegraded) shows a much smaller internal standard peak because the detector sensitivity was lower.
[[:file:oiloil-and-oilsource-rock-correlations_fig8-17.png|Figure 13]] shows gas chromatograms of the saturated hydrocarbons from two seep oils from Papua New Guinea. Both samples contain an internal standard that elutes just before ''n''-C<sub>21</sub>. Because the left oil is biodegraded, the detector sensitivity was set very high to record the trace amounts of remaining ''n''-alkanes. Consequently, the internal standard peak is very tall. In contrast, the right oil (undegraded) shows a much smaller internal standard peak because the detector sensitivity was lower.