A method for detecting and analyzing olefins in petroleum by electrospray ionization mass spectrometry can include obtaining a hydrocarbon sample comprising at least about 90 wt % of saturate compounds; producing a solution comprising the hydrocarbon sample and a metal salt, the metal salt comprising a metal ion; forming olefin-metal ion complexes by electrospray ionization; and detecting the olefin-metal ion complexes using mass spectrometry.