Electrochromatographic behavior of core-shell particles: A comparison study.

Core-shell particle is a new generation high performance packing material for liquid chromatography. Through comparison with a classical totally porous silica phase of the same particle size, we studied Ascentis Express 5 µm core-shell particle's electrochromatographic behavior, in terms of voltage-current property, electroosmotic flow (EOF) and van Deemter curve. It was found, due to the nonpermeable solid core, the core-shell particle presented a diminished EOF and efficiency than the totally porous paricle. This on the other hand proved that the intra-particle pore flow extensively exists and plays an important role in electrochromatography on totally porous material. The core-shell particle's high retentivity led to an enhanced resolution for weakly retained hydrophilic peptides, which were poorly retained and co-eluted on totally porous particles. Further exploration has shown the core-shell material can achieve efficient electrochromatography of protein digests, excellent performance in terms of resolution, reproducibility and long term stability have been observed. The results indicate that the core-shell structure may suggest a reasonable design of stationary phase for bioelectrochromatography of peptides and proteins.