Poly(vinylamine)-coated capillaries with reversed electroosmotic flow for the separation of organic anions

A simple method for the preparation of poly(vinylamine) (PVA) coating on the inner surface of a fused-silica capillary for CE is reported. A high quality PVA was synthesized from acidic hydrolysis of N-vinyl-tert.-butylcarbamate. Based on the reactivity of PVA primary amino groups a coating procedure consisting of two steps: (1) dynamic adsorption of PVA from an aqueous solution, (2) cross-linking of the polymer amino functions with N,N'-methylenebisacrylamide and end-capping of the primary amino groups with an acrylamido derivative bearing quaternary amino functions was devised. A permanent coating that generates a strong anodic electroosmotic flow was produced which is fully compatible with the separation of polyanionic acids, A complete evaluation of reproducibility, efficiency and long-term stability of the coating was carried out using a mixture of eight organic mono-, di- and tricarboxylic acids. The usefulness of PVA-coated capillaries in the analysis of real samples containing UV-transparent organic acids was demonstrated. (C) 1999 Elsevier Science B.V. All rights reserved.