溶解性有机质（DOM）化学组成决定其生物地球化学功能，电喷雾电离源（ESI）结合傅立叶变换离子回旋共振质谱（FT-ICR MS）是表征其分子组成的核心手段。然而由于受电离源及离子传输的限制，全面、准确及可重复的分子组成表征是仍需解决的关键问题。本项目针对DOM体系，研究其电离行为及离子传输效应，阐明不同溶剂对于不同化合物的电离影响及协同效应，建立信号响应与质谱仪器参数间的关系；在此基础上，选择质控样品进行系统性分析表征，对谱图峰形、分辨率和质谱峰强度等关键指标进行考察，形成耦合离子化-离子传输-质量检测参数的优化方案；最后使用建立的方法全面揭示典型DOM的分子组成特征。本项目的成功实施可为环境科学、地球化学等领域的科学研究提供重要的方法支持。项目申请人对环境化学及仪器方法均具有较深刻的理解，所在实验室具有完成FT-ICR MS分析的硬件条件，可以顺利完成该项目。

The chemical composition of dissolved organic matter (DOM) determines its biogeochemical function. Electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has been widely used for molecular characterization of DOMs. However, due to the limitations of ionization sources and ion transmission, comprehensive, accurate and repeatable molecular characterization is still a key issue to be solved. This project will study the ionization behavior and ion transmission effects to clarify the ionization effect and synergistic effect of different solvents on different compounds, and establish the relationship between signal response and parameters of the mass spectrometer. Then, the quality control samples will be selected for systematic analysis, and the key indexes such as peak shape, mass resolution and peak intensity of mass spectrum will be investigated to form an optimization scheme of coupling ionization, ion transmission and mass detection processes. Finally, the molecular composition of typical DOMs will be characterized by the method. The presented project can provide a methodological support for the researches in environmental science and biogeochemistry. The project applicant has a deep understanding of environmental chemistry and instrumental methods, and the laboratory has the FT-ICR MS instrument, so the project can be successfully completed.