| Summary: | Recent research into the sterol content of marine invertebrates has shown that many sterol profiles are extremely complex. Prior to the application of far liquid chromatography in this field the separation of individual sterol molecules into pure components was rather difficult. Subsequently combined cas chromatography-mass spectrometry usinc C.C. stationary phases which are highly thermostable has been found to be extremely useful. The G.C.-M.S. evaluation of a now highly thermostable polar stationary phase PZ-176 for the analysis of complex sterol mixtures is described in Chapter two. Packed column gas chromatography is not capable of resolving all of the components of the most complex sterol mixtures. Therefore high resolution G.C. using glass S.C.O.T. columns has been investigated in detail and Chapter three presents data for a number of columns using cilia-based supports and a variety of polar and non-polar stationary phases. Since the techniques of open tubular G.C. receive scant attention in most published journals, the methods of preparation, installation and routine use of injection and S.C.O.T. columns suitable for sterol analysis are described in detail in Chapter three. Chapter four and five describe the use of mild gel chromatographic method using Sephadex UL-20 and Lipidex 5000, both as a means of obtaining a sterol fraction from an extracted total lipids sample and of fractionating complicated sterol mixtures, allowing minor sterols to be effectively separated from the bulk of the sterol sample prior to final analysis. The methods can be used instead of or in conjunction with conventional adsorption chromatography depending upon the type of sample encountered. Finally the high resolution G.C. and G.C.- M.S. analysis of the sterol content of the red spon Halidona iubens is described in Chapter Six. The sterol mixture is complex and contains several novel marine keto sterols.
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