Soil Organic Matter (SOM): Solvent-Based High Resolution Mass Spectrometry

A limited understanding of the molecular composition of soil organic matter (SOM) inhibits the ability to routinely decipher chemical processes within soil and accurately predict how terrestrial carbon (C) fluxes will respond to changing climatic conditions and land use. To elucidate the molecular-level structure of SOM, organic matter should be extracted from the soil matrix and analyzed using high resolution mass spectrometry (HR MS). Here, we report the use of advanced solvent-based methods and sub-critical fluid extraction protocols for molecular characterization of SOM by HR MS. Combining liquid solvent extraction with super-critical fluid extraction protocols is recommended for extracting a representative fraction of SOM, especially when analysis coverage, recovery, and sensitivity are required. These approaches provide the chemical and structural detail needed to develop mechanistic descriptions of soil C flow processes.