Columns, reversed HPLC carbon loading

The discrepancies with the HPLC method are probably due to the imperfect nature of the C18-silica columns. Some of the new-generation reverse-phase materials, such as C18-alumina, polymeric C18, ultra-high carbon-loaded CT8, and porous graphitic carbon may overcome these problems. A recent development is an immobilized artificial membrane (lAM) column, which should more closely model the biological membranes. 

Reversed-phase HPLC on Cl 8 columns has been the preferred mode for separating carotenoids for quantitative analysis. The popularity of the Cl8 colunm derives from its weak hydrophobic interactions with the analytes (which should make it less destructive than the polar forces in normal-phase OCC), compatibility with most carotenoid solvents and with the polarity range of carotenoids, and wide commercial availability. Many different Cl8 reversed-phase materials are available from different manufacturers, varying in the degree of carbon loading, end capping, and the nature of the bonded phase (i.e., monomeric or polymeric). 

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