RETENTION AND ENANTIOSELECTIVE PROPERTIES OF OVOMUCOID-BONDED SILICA COLUMNS - INFLUENCE OF PHYSICAL-PROPERTIES OF BASE MATERIALS AND SPACER LENGTH

The influence of the physical properties of base silica materials and spacer length on chiral separation of enantiomers on ovomucoid (OVM)-b onded materials was investigated. With regard to the pore size of the base silica materials, the 300-Angstrom materials gave higher enantios electivity than the 120-Angstrom materials, despite the smaller amount s of bonded OVM proteins. However, higher resolution was obtained with the latter materials. With regard to the spacer length, aminopropyl ( AP)-, aminobutyl-, N-(4-aminobutyl)-3-aminopropyl- and N-(6-aminohexyl )-3-aminopropyl-silica gels were activated by N,N'-disuccinimidyl carb onate (DSC) and the proteins were bound. The first two materials showe d excellent chiral resolution properties for the solutes tested, and t he AP materials gave higher enantioselectivity and resolution. On the other hand, only oxprenolol enantiomers were slightly resolved on the last two materials. Also, AP-silica gels activated by DSC were compare d with glycerylpropyl (GP)-silica gels activated by 1,1'-carbonyldiimi dazole. The former materials gave higher resolution for acidic and bas ic solutes despite the lower enantioselectivity, whereas for the uncha rged hexobarbital the latter materials gave higher enantioselectivity and almost equal resolution. The above results reveal that the 120-Ang strom base silica gels are more suitable than the 300-Angstrom base si lica gels for obtaining larger amounts of bonded OVM proteins and that a less hydrophobic spacer such as an AP group and a hydrophilic space r such as a GP group are suitable.