Analysis of modern and fossil plant cuticles by Curie point Py-GC and Curie point Py-GC-MS: Recognition of a new, highly aliphatic and resistant biopolymer

Abstract

This paper investigates to what extent the chemical constituents of plant cuticles (waxes and cutin) can survive diagenesis. Recent and fossil plant cuticles were analyzed by means of Curie point pyrolysis-gas chromatography and Curie point pyrolysis-gas chromatography-mass spectrometry. Recent cuticles were analyzed without treatment, after solvent extraction and after cutin depolymerization. Extensive series of straight-chain alkanes, alk-1-enes and α,ω)-alkadienes dominate the pyrolysates, especially after removal of the wax and cutin. 13C-NMR spectroscopy of the residue after removal of the cutin confirmed the presence of a new, highly aliphatic biopolymer and a polysaccharide fraction. The abundance of straight-chain alkanes, alk-1-enes and α,ω-alkadienes in the fossil plant cuticles indicates the chemical resistence of the biopolymer to diagenesis and may explain the occurrence of straight-chain aliphatic moieties in organic-matter-rich sediments and coals as revealed by “C-NMR spectroscopy and flash pyrolysis methods. The highly aliphatic biopolymer may function as an important oil precursor.