Method to measure olefins in a complex hydrocarbon mixture

Method to measure the quantity of olefin species in a complex hydrocarbon mixture by means of comprehensive multi-dimensional gas chromatography, wherein a sample of the hydrocarbon mixture first passes a first capillary column comprising a dimethyl-polysiloxane stationary phase, the sample further subjected to a thermal modulation before entering a second column comprising a 50% phenyl, equivalent, polysilphenylene-siloxane stationary phase, wherein the introduction bandwidth into the second column in smaller than 20 milliseconds.