A system for characterizing crude oil fractions, comprising: a maltenes sample reservoir containing a maltene sample; a first solvent reservoir containing a solvent for eluting saturates of the maltene sample; a second solvent reservoir containing a solvent for eluting aromatics of the maltene sample; a third solvent reservoir containing a solvent for eluting resins of the maltene sample; a first pump in fluid communication with the first solvent reservoir; a second pump in fluid communication with the second solvent reservoir; a third pump in fluid communication with the third solvent reservoir; a packed bed comprising alumina or silica in fluid communication with each of the first, second, and third pumps and the maltenes sample reservoir; a flowthrough cell in fluid communication with the packed bed for determining an optical density of each of the saturates, aromatics, and resins eluted from the maltene sample; a spectrometer and light source operably associated with the flowthrough cell; and a computer operably associated with the spectrometer, wherein the computer is operable to determine a concentration of each of the eluted saturates, the eluted aromatics, and the eluted resins based upon optical densities over time for each of the eluted saturates, aromatics, and resins using an integral over a curve representing the optical density over time for each of the eluted saturates, aromatics, and resins, wherein eluting the saturates of the maltene sample, eluting the aromatics of the maltene sample, and eluting the resins of the maltene sample is sufficiently complete when the optical density of an eluate generally approaches a baseline value. a maltenes sample reservoir containing a maltene sample; a first solvent reservoir containing a solvent for eluting saturates of the maltene sample; a second solvent reservoir containing a solvent for eluting aromatics of the maltene sample; a third solvent reservoir containing a solvent for eluting resins of the maltene sample; a first pump in fluid communication with the first solvent reservoir; a second pump in fluid communication with the second solvent reservoir; a third pump in fluid communication with the third solvent reservoir; a packed bed comprising alumina or silica in fluid communication with each of the first, second, and third pumps and the maltenes sample reservoir; a flowthrough cell in fluid communication with the packed bed for determining an optical density of each of the saturates, aromatics, and resins eluted from the maltene sample; a spectrometer and light source operably associated with the flowthrough cell; and a computer operably associated with the spectrometer, wherein the computer is operable to determine a concentration of each of the eluted saturates, the eluted aromatics, and the eluted resins based upon optical densities over time for each of the eluted saturates, aromatics, and resins using an integral over a curve representing the optical density over time for each of the eluted saturates, aromatics, and resins, wherein eluting the saturates of the maltene sample, eluting the aromatics of the maltene sample, and eluting the resins of the maltene sample is sufficiently complete when the optical density of an eluate generally approaches a baseline value.