An automated capillary zone electrophoretic system is disclosed. The system employs a capillary cartridge having a plurality of capillary tubes. The cartridge has a first array of capillary ends projecting from one side of a plate. The first array of capillary ends is spaced apart in substantially the same manner as the wells of a microtitre tray of standard size. This allows one to simultaneously perform capillary electrophoresis on samples present in each of the wells of the tray. The system includes a stacked, dual carrousel arrangement to eliminate cross-contamination resulting from reuse of the same buffer tray on consecutive executions from electrophoresis. The system also has a container connected to the detection end of the capillaries. The container is provided with valving which facilitate cleaning the capillaries, loading buffer into the capillaries, introducing samples to be electrophoresced into the capillaries, and performing capillary zone electrophoresis on the thus introduced samples.