Separation of enantiomers on a chiral stationary phase based on ovoglycoprotein .1. Influences of the pore size of base silica materials and bound protein amounts on chiral resolution

The influences of the pore size of base silica gels and the bound amounts of ovoglycoprotein (OGCHI) on the chiral resolution of racemates have been investigated. To the 12-, 20- and 30-nm pare size silica gels, aminopropyl groups were introduced, activated with N,N'-disuccinimidyl carbonate and then reacted with OGCHI followed by blocking with D-glucosamine. For the OGCHI material prepared with the same pore size silica gel, a linear correlation was obtained between the capacity factor of each enantiomer and the amount of bound OGCHI. Enantioselectivity and resolution obtained with the reaction of 40 mg OGCHI per 1 g silica gel were lower than those obtained with the reaction of 80, 160 and 320 mg OGCHI, when the same pore size silica gel was used. This is due to the superfluous achiral interaction with base silica gels and/or spacers because of lower protein coverage. With regard to comparison of the pore sizes of silica gels, the OGCHI materials prepared with the 12-nm pore size silica gel gave the largest capacity factor, and the highest eantioselectivity and/or resolution for the racemates tested, when the same amount of OGCHI was reacted. Thus, the OGCHI materials were prepared with the reaction of 80 mg OGCHI per 1 g silica gel having a 12-nm pore size followed by blocking with D-glucosamine. By diminishing the superfluous achiral interaction with base silica materials and/or spacers, much more efficient OGCHI materials should be obtainable.