Use of 1.5-microm porous ethyl-bridged hybrid particles as a stationary-phase support for reversed-phase ultrahigh-pressure liquid chromatography.

A new ethyl-bridged hybrid packing material was evaluated in terms of its suitability for ultrahigh-pressure liquid chromatography (UHPLC). The 1.5-microm particles were obtained and packed into 30-microm-i.d. fused-silica capillary columns up to 50 cm in length. The particles were evaluated by isocratic reversed-phase UHPLC at pressures up to 4500 bar (65,000 psi). The chromatographic performance of these particles was found to be similar to the performance of 1.0-microm nonporous silica particles. The mechanical strength of the ethyl-bridged hybrid material was evaluated by running a 15-cm-long column at pressures up to 4500 bar. No breakdown of the particles in the packed bed was observed. The sample loading capacity of the hybrid material was evaluated and compared to 1.0-microm nonporous silica material by observing analyte peak width versus amount injected. The observed improvement in loading capacity for the hybrid material versus nonporous silica was consistent with the improvement predicted by comparing the phase ratios of the two materials.