The S2 analyser has been specifically designed to perform preparative pyrolysis for such detail kerogen studies. The pure organic matter or kerogen is deposited in a small boat carved gold rod and introduced in the first part of the oven. A preliminary heating at 60°C for 2 min to get rid of air and the sample is introduced in the oven itself. The oven temperature is first balistically raised to the temperature of thermo-vaporization to eliminate residual light hydrocarbons and water (at 300°C during 3 min) and then the pyrolysis began up to 550 °C with the desired temperature ramp (typically 25°C/min). Outside of the pyrolysis zone, the effluents are condensed with the carrier gas in the trap cooled by liquid nitrogen. When pyrolysis is completed, the trap is disconnected, removed from the liquid nitrogen and allowed to heat slowly. Argon vaporizes and flows out of the trap. The pyrolysate is then dissolved in an appropriate solvent for further analysis.