FUNDAMENTAL-STUDY OF HYDROXYAPATITE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY .2. EXPERIMENTAL-ANALYSIS ON THE BASIS OF THE GENERAL-THEORY OF GRADIENT CHROMATOGRAPHY

In hydroxyapatite (HA) chromatography, competition occurs between the sample molecule and ions from the buffer for adsorption onto the crystal surface of HA. The competition mechanism for several proteins and nucleoside phosphates was analysed on the basis of the general theory of gradient chromatography that has been established recently. It was concluded that the number, x′ of adsorbing sites of HA that are covered by an adsorbed molecule, in general, tends to increase slowly with increase in molecular mass, but that the correlation between molecular mass and x′ is weak. The conclusion is consistent with the deduction made earlier that the stereo-chemical structure of the local molecular surface (which is highly characteristic of a molecule, and is intimately related to the x′ value) is discerned by the regular crystal surface structure of HA. The capacity factor, k′, is argued on the basis of the competition model. © 1990.