Rapid isoelectric focusing of proteins in hydrolytically stable capillaries

Three new types of capillary coatings for capillary isoelectric focusing that avoid siloxane chemistry, resulting in hydrolytically stable coatings, are described and tested: phenyl-silica, acrylamide-reacted vinyl-silica, and pure PTFE. Capillaries of these three types were compared using standard proteins and a biological mixture of proteins similar to what might be encountered in actual use. Of these, the acrylamide-coated capillary produced the highest-quality results. In contrast to capillaries prepared using siloxane reactions, the capillaries described herein exhibited greatly enhanced stability at high pH.