The Bureau of Mines, as a part of American Petroleum Institute research project 60, characterization of the heavy ends of petroleum, has made extensive use of gel permeation chromatography (gpc). Data developed in this study were used to develop several correlations that greatly expanded the usefulness of gpc and the data have been used as an aid in the interpretation of mass spectra (ms). Gpc retention volume data on pure compounds were used with molecular structure to develop correlations that can be used to accurately predict retention volumes, molecular volumes, densities, chain lengths, and ring numbers of many components of petroleum without resorting to further laboratory experimentation. Conversely, the correlation can be used to select or reject some compounds from several possible compounds that are indicated on the basis of ms analysis. The utility of these correlations in compound type characterization is demonstrated by showing their application to 330 deg to 550 deg c fractions from a low-sulfur and a high- sulfur crude oil.