Permanent coated capillaries with reversed electroosmotic flow for anion analysis

Positively charged capillaries for CE with reversed EOF have been prepared by copolymerization of trimethylammoniumstyrene chloride with vinyl groups bonded covalently onto the capillary surface. The EOF was reversed up to pH values of 6 and amounted to the size achievable with uncoated fused-silica capillaries at pH 9, however in the opposite direction. By the addition of acrylamide to the polymerization reactions capillaries could be prepared reproducibly where the EOF was in the anodic direction and was zero at pH values above 7. The coating is stable up to pH of 10. Application of these capillaries for anion separations are shown. (C) 1998 Elsevier Science B.V. All rights reserved.