ABSTRACT
Some polyunsaturated hydrocarbons, the carotenes, play an important role in photosynthesis and are responsible for the orange to red color of several plant products. Unsaturated hydrocarbons such as squalene appear in many eukaryotic cells as intermediates in the biosynthesis of more complex isoprenoid compounds such as cholesterol. The most common forms of polyunsaturated hydrocarbons containing unconjugated double bonds are squalene. Hydrocarbons occur in total lipid extracts and in unsaponifiable lipids derived from most natural sources, although the distribution of particular hydrocarbons may be quite selective. Micro-determination of the amounts of hydrocarbons in natural sources is probably simplest for those that absorb light in the visible or UV range, that is primarily carotenoids and their precursors. The use of a sophisticated on-line photodiode array detector to determine the absorption spectrum of each peak provides a powerful micro-assay system. Sensitive assays for saturated and simple unsaturated hydrocarbons are best based on gas-liquid chromatography in which micro-detection and quantitation present no difficulties.
