CHARACTERIZATION OF UNRESOLVED COMPLEX-MIXTURES OF HYDROCARBONS IN PETROLEUM

ALTHOUGH petroleum is an important energy resource, there is still much to learn about its composition that would be of practical importance in exploration, refining and the identification of materials resulting from oil spills. Chromatography does not resolve (and thus identify) a substantial proportion of even the hydrocarbons in petroleum. These components are often referred to as the unresolved complex mixture (UCM), or 'hump', which is especially pronounced for biodegraded petroleum and certain refined fractions such as lubricating oils1-4. We now describe the use of several methods in parallel to analyse the hydrocarbon hump from crudes, lubricating oils and oil-spill samples. Comparison of our results with those for synthesized alkanes allows us to propose model structures for some of the hydrocarbon components of the hump, and from in vitro studies we conclude that the resistance of many of these compounds to microbial degradation arises partly from their structure. © 1990 Nature Publishing Group.