Characterization of nitrogen-containing species in Huadian shale oil by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

► Nitrogen compounds in Huadian shale oil (HDSO) was characterized by ESI FT-ICR MS. ► The N1 and N1O1 are the most abundant in all nitrogen-containing classes in HDSO. ► The basic Nx class species predominate in all basic nitrogen species of HDSO. ► Most N1 and N1O1 class species in HDSO contain 1-7 aromatic rings. ► The alkyl pyridines with 20-33 carbon atoms are rather rich in HDSO.