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 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 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 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. <EOS>