A procedure is described for joining capillaries of the same outer diameters. The ends of the capillaries to be joined are evenly polished and capillaries are placed against one another with polished ends pressed together in a simple Plexiglas holder. The junction obtained does not contribute to separand zone distortion and broadening, does not cause deterioration in the separand resolution and is mechanically stable. (C) 1998 Elsevier Science B.V.