An oil or a bitumen (soxhlet extract of source rock) can be fractionated in two fractions: maltenes and asphaltenes. The asphaltene fraction is removed by precipitation in a light hydrocarbon solvent (n-Pentane) followed by filtration. n-Pentane is added to the sample in a volume ratio of 10:1. The mixture is mixed in a vortex mixer in low speed and then is filtrated through a 0.45 micron filter cartridge. n-Pentane and maltenes are collected in a pre-weighed vial and evaporated to dryness in Nitrogen stream. Asphaltenes are removed from the filter by rinsing with chloroform and collected in a pre-weighed vial. Chloroform is evaporated to dryness in Nitrogen stream.