PERFLUOROOCTYL AND PERFLUOROBUTYL BONDED ALUMINA STATIONARY PHASES FOR HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

The preparation and properties of perfluorooctylalumina (PFOA) and per fluorobutylalumina (PFBA) high performance liquid chromatographic stat ionary phases have been investigated. The PFOA phase was produced by c hemisorption of perfluorooctanoic acid onto the surface of alumina. Th e PFBA phase was produced by a similar adsorption of perfluorobutylpho sphonic acid onto alumina. Both phases exhibit reverse phase liquid ch romatographic properties. Elemental analyses of these materials indica ted that alkyl group surface coverage of the PFBA phase is higher than that of the PFOA phase. In contrast, retention of solutes on the PFBA phase is lower than that of PFOA. Isocratic capacity factors of over 20 compounds on the PFOA and PFBA phases were determined and compared with those obtained on octadecylalumina (ODA) and octadecylsilica (ODS ) phases. In contrast to the greater retention of phenols than other c ompounds that was evident on the unfluorinated ODA phase, the retentio n of phenols on the PFOA and PFBA phases was not found to be significa ntly different from that of other compounds. These results are attribu ted to a reduced degree of hydrogen bonding interactions between pheno lic solutes and the PFOA and PFBA phases compared to those which occur between phenols and the ODA phase. preliminary investigations of the utilization of the PFOA phase for the separation of peptides and the e mployment of the PFBA phase for the rapid separation of phenols are al so described.