Unresolved Complex Mixture

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Examples of non-biodegraded crude oil (top) and a heavily biodegraded one (bottom) with the UCM area indicated. Both chromatograms have been normalized so that their integrals are equal to unity.
Examples of non-biodegraded crude oil (top) and a heavily biodegraded one (bottom) with the UCM area indicated. Both chromatograms have been normalized so that their integrals are equal to unity.

Unresolved Complex Mixture (also UCM or hump) is a feature frequently observed in gas chromatographic (GC) data of crude oils and other substances. The reason for its appearance is that GC cannot resolve and identify a significant part of the hydrocarbons in crude oils. The resolved components appear as peaks while the UCM appears as a large background/platform. In non-biodegraded oils the UCM may comprise less then 50 % of the total area of the chromatogram, while in biodegraded oils this figure can rise to around 90 %. UCM is also observed in certain refined fractions such as lubricating oils ([1] and references therein).

[edit] See also

  • Gas-liquid chromatography

[edit] References

  1. ^ Gough, M. A. & Rowland, S. J. (1990) Characterization of unresolved complex mixtures of hydrocarbons in petroleum. Nature 344, pp. 648-650
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