High molecular weight polyarginine as a capillary coating for separation of cationic proteins by capillary electrophoresis

Fused silica capillaries treated with dilute solutions of high molecular weight polyarginine (PA) provide capillary electrophoresis separation efficiencies of more than 2 million theoretical plates per meter and improved migration time reproducibility for the analysis of protein mixtures. The non-covalently bound PA coating was stable for several days and could be easily regenerated by exposing the capillary to a dilute solution of PA for several minutes. A comparison of PA and polybrene (PB) treated capillaries indicates that the PA capillary is capable of providing higher separation efficiencies, but that PB provides a more stable coating when used under acidic conditions and with high ionic strength buffers.