ABSTRACT
Detailed sterol analysis is required at all stages of the functional foods development process and later production. Evidently the complexity of the matrix and the concentration levels differ significantly when comparing a raw material with a biofluid sample. However, in contrast to what one might expect at first glance, one single GC method suffices for all of these applications. The sample preparation of the various samples, on the other hand, will be very difficult. To a first approximation it could be stated that the sample preparation method is largely determined by the matrix, whereas the chromatographic method required is determined only by the degree of detail desired. In detailed sterol analysis saponification is widely applied. With only minor adjustments it can be used for the analysis of pure raw materials as one extreme of the analytical spectrum, to biofluids at the other extreme. The only analytically relevant difference between these samples when considering saponification is the concentration difference. Whereas pure materials contain the individual sterols at levels exceeding 50%, the concentrations in plasma samples can be as low as submicromolar concentration for an individual sterol. An example of the analysis of sterols in blood is shown in Fig. 10. Here approximately 0.5g of sample, the maximum that is available in most animal or human trials, is saponified and the final extract is reconstituted in 50µL solvent of which 1µL is injected on-column. To compare this with raw material analysis: in raw
