地质环境中生物标志物 GDGTs 分析技术研究进展

Research Progress in Analytical Methods of Biomarker GDGTs in Geological Environments

甘油二烷基甘油四醚脂(GDGTs)是一类来自于微生物细胞膜脂的新兴生物标志物,广泛存在于海洋、湖泊、土壤、泥炭等环境。在活体细胞中,GDGTs通常以完整极性膜脂(IPL-GDGTs)的形式存在,而在地质环境中主要以脱去极性头基的核心脂(CL-GDGTs)的形式存在。CL-GDGTs结构稳定、不易降解,并且对环境变化响应敏感,因此被认为是重建古气候-古环境变化的有力工具。GDGTs结构复杂、种类多样,在环境中的含量通常较低且常与其他化合物共存,因此分析难度较高,现有技术和方法在其分离、纯化、定量等方面仍然面临挑战。本文总结了近年来GDGTs在分析技术方面的研究进展,概述了GDGTs的分类与结构,对环境中IPL-GDGTs和CL-GDGTs的分离、纯化等方法进行总结和比较,其中CL-GDGTs可选择多种提取方法,而极性较强、热稳定性较差的IPL-GDGTs应尽量选取Bligh-Dyer提取法。普通的分离、纯化通常采用柱层析法,而涉及GDGTs单体分离时,一般采用制备液相色谱法。液相色谱-质谱、核磁共振波谱、气相色谱-同位素比值质谱是GDGTs含量测定、结构鉴定、同位素分析的主要分析手段。本文评述了现有方法的特点和不足,并在此基础上,提出了GDGTs分析技术的发展方向,以期为地质环境中GDGTs的分析研究提供启示和参考。

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 CLGDGTs 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.