A protein-encapsulation technique by the sol-gel method for the preparation of monolithic columns for capillary electrochromatography

A novel protein-encapsulation technique using sol-gels was developed for the preparation of monolithic capillary columns for capillary electrochromatography. Two chiral compounds, bovine serum albumin (BSA) and ovomucoid (OVM) from chicken egg white, were encapsulated in tetramethoxysilane-based hydrogel and their chiral selectivity was evaluated for the separation of some selected enantiomers (tryptophan, benzoin, eperisone, chlorpheniramine). The protein encapsulation was carried out within a capillary in a single step under mild conditions. The resultant monolithic columns showed adequate chromatographic performance, including mechanical strength, penetration of pressurized flow, and chiral separation. Two different proteins, BSA and OVM, were successfully encapsulated into the gel matrixes by changing the alkoxy-silane compositions of the gel. Run-to-run repeatability was quite satisfactory. The consecutive analysis of the neutral compound, benzoin, by the OVM-encapsulated column showed good repeatability in the retention time (RSD = 1.23% for the first peak, N = 10). Under optimized conditions, the theoretical plate number for the first peak of benzoin reached 72 000 plates/m.