capillary tubes useful for performing capillary zone electrophoresis separation techniques are prepared by precoating the capillary tubes with an adhesive agent , preferably a dilute agarose phase . the analytical agarose - based media then is positioned in the tubes , where it adheres to the earlier coating . the analytical media exhibits strong structural integrity and adheres well to the capillary tubes ; moreover , the media is suitable for capillary zone electrophoretic separation of biopolymers .