Polydopamine assisted liquid phase deposition for preparation of zirconia coated column in capillary electrophoresis

A zirconia coated column was prepared for capillary electrophoresis separation based on a mussel adhesive protein inspired polydopamine coating for the first time. Polydopamine, formed by the spontaneous oxidative polymerization of dopamine under alkaline conditions, was used to immobilize zirconia onto the inner surface of a capillary via a liquid phase deposition process. During the formation of zirconia, the outer hydroxyl groups of the polydopamine layer can chelate with Zr⁴⁺ to boost nucleation and growth of zirconia. The existence of the zirconia coating was successfully confirmed by using X-ray photoelectron spectroscopy and a comparative study of electroosmotic flow. Furthermore, the zirconia coated capillary was applied in the separation of inorganic anions and alkaloids and baseline separations were achieved with good reproducibility and stability. Therefore, the presented method is anticipated to be a promising preparation technology for metal oxide coated columns, characterized by a simple preparation process, mild reaction conditions and high efficiency.