Infrared spectroscopy quantification of functional carbon groups in kerogens and coals: A calibration procedure

The determination of the abundances CHx, C = O and aromatic groups in chondritic Insoluble Organic Matter (IOM) coals by Infrared (IR) spectroscopy is a challenging issue due to insufficient knowledge on absorption cross-sections their sensitivity molecular environment. Here, we report calibration approach based 13C synthetic model material whose composition was unambiguously determined Direct-Pulse/Magic Angle Spinning Nuclear Magnetic Resonance (DP/MAS NMR). Ratios have been determined, method has applied IOM samples extracted from four chondrites as Orgueil (CI), Murchison (CM), Tagish Lake (C2-ungrouped) EET 92042 (CR2), series coals. estimate aliphatic carbon ratio (nCHx/nAro) Orgueil, good agreement with Single-Pulse/NMR estimates earlier published, lower factor 1.3 case CR chondrite (but error bars overlap). In contrast, carbonyl (nCHx/nC=O) overestimated for chondrites. These discrepancies are likely control cross-section bonds local Regarding coals, use published NMR analyses brought light that integrated ACHx/AAro varies vitrinite reflectance over an order magnitude. Here well, oxygen speciation plays critical AAro, which decreases increasing reflectance. We provide analytical law links reflectance, will allow nCHx/nAro any coal sample, provided its known.