A new method for analysis of saturates in vacuum residue was developed by solid phase extraction and field desorption time-of-flight mass spectrometry. Vacuum residue was separated into saturates, aromatics, and resins by solid phase extraction. Saturates were ionized by field desorption source which produces primarily unfragmented mass spectra. This method could be applied for carbon number and compound-type distribution analysis of paraffins and 1-ring to 6-ring cycloparaffins in different vacuum residues. Molecular composition of saturates from various vacuum residue were characterized successfully by the developed method. (C) 2013 Elsevier Ltd. All rights reserved.