Pressurized liquid extraction of selected molecular biomarkers in deep sea sediments used as proxies in paleoceanography

Pressurized liquid extraction has been performed on a suite of deep-sea sediments to assess its capability as an extraction technique in the analysis of molecular biomarkers used in paleoceanography. Specific compounds assessed comprise long-chain alkenones, n-alkanes, n-alcohols and, additionally, one diol and one keto-ol. These have been extracted by both pressurized liquid extraction and ultrasonication for comparison. One key result is that the UK′37 index (based on the degree of unsaturation of the alkenones and used as a paleothermometer in paleoceanography) remains intact after both extraction techniques. In terms of biomarker concentrations, which are often used to qualitatively assess changes in marine productivity and/or terrigenous inputs, pressurized liquid extraction is substantially more efficient than ultrasonication, providing higher amounts of extracted constituents, particularly for polar compounds.