SYNTHESIS AND EVALUATION OF ANIONIC POLYMER-COATED CAPILLARIES WITH PH-INDEPENDENT ELECTROOSMOTIC FLOWS FOR CAPILLARY ELECTROPHORESIS

A capillary coating method was developed using a sodium-2-acrylamido-2 -methylpropanesulfonate (NaAMPS) polymer. Capillaries coated with this anionic polymer exhibited pH-independent electroosmotic flows (EOFs). Capillaries with a particular EOF rate could be synthesized simply by changing the molar ratio of NaAMPS to neutral acrylamide in the polym er mixture. The pH-independent EOF of the coated capillary changed les s than 1.5% over 20 days of routine, intermittent use. Capillary lifet ime with a continuously applied electric field of 286 V cm(-1) was abo ut 60 h. Reproducibility of the coating procedure was 1.7% R.S.D. in o bserved EOF for independently synthesized capillaries. The pH-independ ent EOF of these capillaries as well as their selectable flow-rates (v ia synthesis) should prove useful in micellar electrokinetic capillary chromatography (MECC) at low pH values and for expansion of the separ ation window in MECC, as well as for more versatile separations of var ious species in the capillary zone electrophoresis mode.