John E. O'Gara

Porous Hybrid Organic‐Inorganic Particles in Reversed‐Phase Liquid Chromatography

Abstract Reversed‐phase chromatographic media have recently become available that are based on porous hybrid organic‐inorganic particles. The present paper reviews hybrid particles that are made from organosilanes (organic moiety) and tetraalkoxysilanes (inorganic moiety). The hybrid particles are defined and classified within the context of a broader definition of hybrid materials. First syntheses and chromatographic evaluations are discussed for this class of hybrid packing materials. Publications are then described, which characterize two distinguishing chemical properties of hybrid particles vs. silica gel: 1) less acidic silanols, and 2) markedly longer lifetimes in alkaline mobile phases. These properties are achieved without sacrificing mechanical strength, as is found for fully organic particles, i.e., polymers, with the same chemical features. Literature reports are then reviewed that employ hybrid based reversed‐phase column packings for HPLC. Topics covered include fundamental retention mechanism studies, methods development studies, and applications made possible with the hybrid based products. Further review is presented on the use of theses hybrid particles for UPLC. The hybrid particles afford good mechanical strength without sacrificing retention and loading capacity, as is found for non‐porous particles. Applications employing hybrid based particles in the UPLC mode are then reported.