Research Progress in Analytical Methods of Biomarker GDGTs in Geological Environments

Glycerol dialkyl glyceryl tetraethers (GDGTs) are a class of environment biomarkers that are widely found in the environment of oceans, lakes, soils, and peat. GDGTs usually exist as intact polar lipids (IPL-GDGTs) in living cells, while they exist as core lipids stripped of polar head groups (CL-GDGTs) in geological environments. CL-GDGTs are structurally stable and sensitive to environmental changes and are considered to be a powerful tool for reconstructing palaeoclimate-palaeoenvironmental changes. GDGTs are structurally complex and diverse, coexisting with other compounds and present low contents, which brings challenges in analysis, especially in separation, purification, and quantification. This article summarizes the classification and structure of GDGTs, and presents a summary and comparison of methods for the separation and purification of IPL-GDGTs and CL-GDGTs in the environment. Multiple extraction methods can be used for CL-GDGTs, while the polar and thermally unstable IPL-GDGTs are preferably extracted using the Bligh-Dyer method. This article reviews the characteristics and limitations of various analysis methods, including liquid chromatography-mass spectrometry, nuclear magnetic resonance spectroscopy, and gas chromatography-isotope ratio mass spectrometry. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202306100077.