Identification of acidic NSO compounds in crude oils of different geochemical origins by negative ion electrospray Fourier transform ion cyclotron resonance mass spectrometry

We present the selective ionization, resolution and identification of acidic NSO compounds in three crude oils of different geochemical origins by negative ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Selective ionization by ESI affords direct detection of neutral nitrogen compounds and carboxylic acids in petroleum without pre-chromatographic isolation. Ultra-high resolution/mass accuracy allows detailed and positive identification of acidic NSO compounds in the crude oils. Observed compositional differences reflect known crude oil properties/histories. Collectively, 14,000 masses, spanning 18 different heteroatomic classes, are identified unequivocally, demonstrating the potential of ESI-FT-ICR MS for geochemical applications.