Changes

==4-methylsteranes==

==4-methylsteranes==

[[file:oiloil-and-oilsource-rock-correlations_fig8-25.png|thumb|200px|{{figure number|3}}Distribution of 4-methylsteranes in selected rock extracts. Modified from Summons et al.;<ref name=ch08r52>Summons, R., E., Thomas, J., Maxwell, J., R., Boreham, C., J., 1992, Secular and environmental constraints on the occurrence of dinosteranes in sediments: Geochimica et Cosmochimica Acta, vol. 56, p. 2437–2444, DOI: 10.1016/0016-7037(92)90200-3.</ref> reprinted with permission from Elsevier.]]

[[file:oiloil-and-oilsource-rock-correlations_fig8-25.png|thumb|200px|{{figure number|3}}Distribution of 4-methylsteranes in selected rock extracts. Modified from Summons et al.;<ref name=ch08r52>Summons, R. E., J. Thomas, J. R. Maxwell, and C. J. Boreham, 1992, Secular and environmental constraints on the occurrence of dinosteranes in sediments: Geochimica et Cosmochimica Acta, vol. 56, p. 2437–2444, DOI: 10.1016/0016-7037(92)90200-3.</ref> reprinted with permission from Elsevier.]]

MRM analysis is useful in distinguishing ''n''-propylcholestanes from 4-methylsteranes and in assigning identities to different types of 4-methylsteranes. This sophisticated GC/MS analysis method will probably become commonplace because of its specificity in oil–oil and oil–source rock correlation efforts.

MRM analysis is useful in distinguishing ''n''-propylcholestanes from 4-methylsteranes and in assigning identities to different types of 4-methylsteranes. This sophisticated GC/MS analysis method will probably become commonplace because of its specificity in oil–oil and oil–source rock correlation efforts.