期刊
ANALYTICAL CHEMISTRY
卷 94, 期 6, 页码 2973-2980出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.analchem.1c05018
关键词
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资金
- NSF Division of Chemistry and Division of Materials Research [DMR-1644779]
- State of Florida
- National Science Foundation [1512670, 2114868]
- USDA National Institute of Food Agriculture through AFRI [2021-67019034608]
- AFRI from the USDA National Institute of Food and Agriculture [2021-67019-33726]
- Directorate For Engineering
- Div Of Chem, Bioeng, Env, & Transp Sys [1512670] Funding Source: National Science Foundation
- Division Of Environmental Biology
- Direct For Biological Sciences [2114868] Funding Source: National Science Foundation
This study utilized high-resolution mass spectrometry to achieve the separation and quantification of organic nitrogen in wildfire-impacted systems for the first time, providing new insights into the impact of wildfires on organic carbon and nitrogen cycling.
Wildfires affect soils through the formation of pyrogenic organic matter (pyOM) (e.g., char and soot). While many studies examine the connection between pyOM persistence and carbon (C) composition, nitrogen (N) transformation in wildfire-impacted systems remains poorly understood. Thermal reactions in wildfires transform biomass into a highly complex, polyfunctional, and polydisperse organic mixture that challenges most mass analyzers. High-field Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) is the only mass analyzer that achieves resolving powers sufficient to separate species that differ in mass by the mass of an electron across a wide molecular weight range (m/z 150-1500). We report enhanced speciation of organic N by positive-ion electrospray ionization (ESI) that leverages ultrahigh resolving power (m/Delta m(50%) = 1 800 000 at m/z 400) and mass accuracy (<10-100 ppb) achieved by FT-ICR MS at 21 T. Isobaric overlaps, roughly the mass of an electron (M-e- = 548 mu Da), are resolved across a wide molecular weight range and are more prevalent in positive ESI than negative ESI. The custom-built 21 T FT-ICR MS instrument identifies previously unresolved mass differences in CcHhNnOoSs formulas and assigns more than 30 000 peaks in a pyOM sample. This is the first molecular catalogue of pyOM by positive-ion ESI 21 T FT-ICR MS and presents a method to provide new insight into terrestrial cycling of organic carbon and nitrogen in wildfire impacted ecosystems.
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