Extended hopanes beyond C40 in crude oils and source rock extracts from the Liaohe Basin, N.E. China

A series of 17α(H),21β(H)-hopanes and 17β(H),21α(H)-moretanes up to C44 has been identified in crude oils and source rock extracts in the Liaohe Basin, N.E. China. This result extends the previously known homologous series reported up to C40 for 17α(H),21β(H)-hopanes and C35 for 17β(H),21α(H)-moretanes. These compounds may be viewed as the representatives of a new class of molecules whose natural distribution and biological significance remains to be determined, although the possibility of diagenetic modification of the known hopane precursors cannot be ruled out.