Cross-linked polymer coatings for capillary electrophoresis and application to analysis of basic proteins, acidic proteins, and inorganic ions

A coating process for covalent coupling of fully formed polymers to silane-treated capillaries is described. The coupling process occurs through free-radical sites created on both the silane and polymer during the polymer cross-linking process. Coupling and cross-linking take place simultaneously, resulting in a densely cross-linked layer on the capillary surface. By using this coating procedure, several polymers, such as polyacrylamide (PA), poly(vinylpyrrolidone) (PVP), and poly(ethylene oxide), were successfully anchored on capillaries treated with silanes such as (methacryloxypropyl)trimethoxysilane. (MET), chlorodimethyloctylsilane (OCT), and trimethyoxyallylsilane. High-resolution separations of basic proteins with achieved using efficiencies of 500 000 plates/50 cm were achieved using polymer-coated capillaries such as MET-PVP, MET-PA, and OCT-PCP. Similarly, high-resolution separations of milk proteins and hemoglobin variants were achieved by a MET-PVP-coated capillary. In addition to neutral polymers, the above coupling process was also suitable for attaching cationic polymers, Fast and efficient separations of acidic proteins and small inorganic anions were achieved using an acrylamide-based cationic polymer-coated capillary. The coating process described here is easy to implement and results in reproducible, stable capillary coatings for capillary electrophoresis.