Chromatography dissolution modes

Several LC modes have been used for the separation of fat-soluble vitamins. The choice depends on the vitamin forms to be determined, the nature of the food matrix, and the sample treatment. Adsorption chromatography has two main advantages (a) geometric and positional isomers are generally resolved on silica stationary phases [86,87] (b) relatively high loads of lipoidal material can be tolerated by this type of column. The latter feature allows the direct injection of extracts obtained by means of direct liquid extraction [88] or sample dissolution in hexane (e.g., vitamin E from oils) [89], when the recourse to saponification is not essential for the analyte isolation. In these cases, fluorescence detection is... 

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