Simultaneous extraction and chromatographic separation of n-alkanes and alkenones from glycerol dialkyl glycerol tetraethers via selective Accelerated Solvent Extraction: Note

Auderset, Alexandra, Schmitt, Mareike and Martínez-García, Alfredo (2020) Simultaneous extraction and chromatographic separation of n-alkanes and alkenones from glycerol dialkyl glycerol tetraethers via selective Accelerated Solvent Extraction: Note. Organic Geochemistry, 143 (5), [103979]. (doi:10.1016/j.orggeochem.2020.103979).

Abstract

A method is described for simultaneous extraction and chromatographic separation of saturated hydrocarbons (n-alkanes) and unsaturated long-chain ketones (alkenones) from glycerol dialkyl glycerol tetraethers (GDGTs) using selective accelerated solvent extraction (ASE). We show that the method can be used to successfully separate n-alkanes and alkenones from GDGTs in marine sediment samples and n-alkanes from GDGTs in lake sediments and soil samples. A comparison of our method with analysis of samples purified using classical silica column chromatography demonstrates that the new method does not affect the alkenone unsaturation index (UK³⁷), the TetraEther indeX (TEX₈₆), the Methane Index (MI), the Ring Index (RI), the branched-GDGT-based paleotemperature and soil pH indices, the Branched and Isoprenoid Tetraether (BIT) index, the n-alkane average chain length (ACL) or the carbon preference index (CPI). The new procedure results in higher sample recoveries for n-alkanes and more precise UK³⁷ estimates at low concentrations, and contributes to reduced analyst laboratory time.

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Contributors

Author: Alexandra Auderset

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