Fritless capillary electrochromatography

The preparation of packed capillaries with stable frits of good quality can be a hurdle to obtain efficient separations in capillary electrochromatogr aphy (CEC). Especially with particles smaller than 3 mu m, frit preparation is cumbersome. Highly efficient separations using packed capillaries witho ut frits are presented. Under appropriate CEC conditions the particles were retained by electrophoretic attraction towards the anode by a tapered capi llary inlet, without the need of a frit at the outlet end. Such fritless ca pillaries, packed with 1.5 mu m nonporous reversed-phase particles, allowed separations with efficiencies of more than 500000 plates/m. Once the capil laries were conditioned properly, more than 100 separations could be perfor med with good repeatability. With respect to separation efficiency, fritles s capillaries packed with 3 mu m particles were comparable with standard CE C capillaries with frits. Examples of separations of steroids, a pesticide and its by-products, and cardiac glycosides under various CEC conditions ar e shown.