"The efficient utilization of petroleum requires processing of the heavy residua remaining after a vacuum distillation of crude oil. The amounts of residue, its physical properties and chemical composition depend upon a crude oil source. A knowledge of the chemical composition of petroleum residua is still rather limited, although there have been many efforts in the past to develop methods for analyzing these complex mixtures. As a result of the American Petroleum Institute Research Project 60, a separation-characterization scheme for compound-type analysis of high-boiling (375-675 degrees C) distillates was developed with. Very recently, the work done in this laboratory on the compound-type composition of 675 degrees C residua from four crude oils—Recluse (Wyo.), Gach Saran (Iran), South Swan Hills (Alta) and Wilmington (Calif.)—has been published (3, 4, 5). This paper describes the separation and characterization of 675 degrees C residue of the Russian crude oil that is supplied through a pipeline from Siberian oil fields to Poland and East Germany. In successive separation steps that include (a) chromatography on ion-exchange resins, (b) coordination chromatography on ferric chloride-Attapuigus clay and (c) chromatography on silica the total 675 degrees C residue is separated into five major compound-class fractions. The emphasis in this study is on polar heteroatom-containing compound types that are generally regarded as being a major problem in conversion of heavy residua to fuels. Compound types having nitrogen and oxygen-containing functional groups were of particular interest. The sulfur-containing groups were not investigated in this study. The compound-type composition of the 675 degree C residue of the Russian crude oil is comtured with those of 675 degree C residua of crude oils previously investigated."