Interfacial Material in Water-in-Oil Emulsions Characterized by ESI(−) FT-ICR MS: Evaluation of the Influence of Centrifugation Conditions

Emulsion represents a major challenge in the petroleum industry due to its stabilization promoted by polar fractions. In this study, interfacial material (IM) residues were isolated from a naturally emulsified crude oil using a centrifugation-based methodology under different times and temperature conditions. The recovered interfacial materials were characterized by negative-ion electrospray Fourier transform ion cyclotron resonance mass spectrometry (ESI(−) FT-ICR MS). Results showed that longer centrifugation times and higher temperatures reduced the abundance of nitrogen species while enriching oxygenated classes, particularly naphthenic acids and mixed heteroatomic species. Highly aromatic compounds migrated into NO₂[H] and NO₃[H] classes, whereas both linear and aromatic naphthenic acids, O₂[H] class, became more prominent. Van Krevelen diagrams confirmed the increase in aromaticity of the IMR compared with the original emulsion. These findings highlight the role of centrifugation parameters in modulating the composition of IM and provide new insights into the molecular species responsible for emulsion stability.