Laser desorption/ionization techniques in the characterization of high-molecular-weight oil fractions--Part 2: De-asphalted oils.

The composition of the de-asphalted oil fraction obtained from two different Italian fields was studied by laser desorption/ionization mass spectrometry. These fractions were treated with different solvent mixtures, and subfractions containing saturates, aromatic and polar compounds were obtained and analyzed by the same instrumental approach.The investigation showed clear differences between the samples coming from the two oils. The instrumental approach did not lead to an accurate description of the different components in terms of elemental composition and structures; however, valid information could be obtained on the molecular weight distribution of the components of the different fractions.