Peptides--Separation

The applicability of a recently developed octadecylalumina (ODA) stationary phase for the preparative separations of proteins and peptides is compared with that of conventional Octadecylsilica (ODS) phases. Chromatographic peak widths, peaks areas, and recoveries of polypeptides were obtained from both types of phases. The ODA phase compares favorably with the ODS phase on small peptides, but exhibits low recoveries on high molecular weight proteins. The results are attributed to the unique fused-microplatelet shape of the ODA particles.

The performance of several alkyl-bonded alumina-based stationary phases was evaluated by comparing the separation of synthetic octapeptide and polypeptide mixtures and tryptic digests of larger proteins. These phases were of differing pore diameter, alkyl chain length modification and particle shape and size. The separations were compared to standard silica phases. The narrow pore octadecyl bonded alumina phase outperformed the other alumina and silica phases in terms of separation efficiency and mobile phase resistance. Superior performance is attributed to the enhanced solute mass transfer properties and the unique morphology of the microplatelet alumina particles. The mechanism of separation gradually changes with increasing size of the peptide.