Distribution of Acyclic Isoprenoids in Fractions from Stepwise Oxidation of Green River Kerogen

Abstract

A study on the distribution of isoprenoid structures in the five fractions obtained by mild Na2Cr2O7/AcOH stepwise oxidation of Green River kerogen is presented. Gas chromatography-mass spectrometry analysis of the fractions resulted in the identification of a homologous series of isoprenoid acids ranging from C14-C21 with C16 as the largest and C18 entirely absent, as well as the two isoprenoidal ketones: 6,10-dimethyl-2-undecanone and 6,10,14-trimethyl-2-pentadecanone. A semi-quantitative analysis of these components was performed using an INCOS 2300 data system. On the basis of the results obtained, it is sugested that isoprenoid structures do not constitute more than 4% of the kerogen matrix. The reuslts also substantiate previous assumptions that the phytol side chain of chlorophyll is the most likely pregenitor to the chain isoprenoids found in Green River kerogen.