A multi-channel cartridge for bio-separation of a sample, which is configurable to accommodate a desired one of a first capillary column and a second capillary column, comprising: a plurality of cartridge elements, wherein each cartridge element defines a different separation channel, and wherein each cartridge element comprises: a body defining an opening as a detection window for receiving external detection optics; a capillary column (10, 10') supported in the body; a reservoir attached to a first end of the body in fluid flow communication with a first end of the capillary column, wherein the reservoir is dedicated to a single cartridge element; an anode, wherein the anode is conductively coupled to fluid contained in the reservoir; and a cathode disposed at a second end of the body, wherein the cartridge elements are coupled, characterized by: wherein the reservoirs of the respective cartridge elements are not in flow communication, wherein the anodes of the respective cartridge elements are not conductively coupled in the multi-channel cartridge, wherein, as desired, the multi-channel cartridge is configurable between a first configuration in which the first capillary column having a first length is configured to extend between the reservoir of a cartridge element and the cathode of said cartridge element to expose a section along the first capillary column in the detection window of said cartridge element, and a second configuration in which the second capillary column having a second length longer than the first length is configured to extend between the reservoir of a first cartridge element and a cathode of a second cartridge element to expose a section along the second capillary column in the detection window of the first cartridge element, wherein the exposed sections of respective first and second capillary columns are aligned with the external optics through the respective detection windows. a plurality of cartridge elements, wherein each cartridge element defines a different separation channel, and wherein each cartridge element comprises: a body defining an opening as a detection window for receiving external a body defining an opening as a detection window for receiving external detection optics; a capillary column (10, 10') supported in the body; a reservoir attached to a first end of the body in fluid flow communication with a first end of the capillary column, wherein the reservoir is dedicated to a single cartridge element; an anode, wherein the anode is conductively coupled to fluid contained in the reservoir; and a capillary column (10, 10') supported in the body; a reservoir attached to a first end of the body in fluid flow communication with a first end of the capillary column, wherein the reservoir is dedicated to a single cartridge element; an anode, wherein the anode is conductively coupled to fluid contained in the reservoir; and wherein the reservoirs of the respective cartridge elements are not in flow communication, wherein the anodes of the respective cartridge elements are not conductively coupled in the multi-channel cartridge, wherein, as desired, the multi-channel cartridge is configurable between a first configuration in which the first capillary column having a first length is configured to extend between the reservoir of a cartridge element and the cathode of said cartridge element to expose a section along the first capillary column in the detection window of said cartridge element, and a second configuration in which the second capillary column having a second length longer than the first length is configured to extend between the reservoir of a first cartridge element and a cathode of a second cartridge element to expose a section along the second capillary column in the detection window of the first cartridge element, wherein the exposed sections of respective first and second capillary columns are aligned with the external optics through the respective detection windows.