Derivatization of Silica for Normal and Reverse Phase Chromatography

1b Derivatization of Silica for Normal and Reverse Phase Chromatography 

An important property of sihca particles for chromatographic stationary phases is the reactivity of the hydroxyl groups on the surface, which permits derivatization to provide a wide range of properties. The silanol groups are weakly acidic, with a concentration on the surface of porous sihca 8p,mol.m , i.e. 5 Si—OH groups per 100 A, corresponding to an average inter-silanol separation 5A. Derivatization is almost always 

For nonpolar functional groups R, the most commonly used choices for reverse-phase separations are alkyl-bonded phases with R = CgHjy and C18H37, though R = CH3 and C4H9 have applications for protein separations. (Note that the —Si(CH3)2CigH37 functional group is frequently referred to as octadecylsilyl 

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