Dual electrode injection of analyte into a capillary electrophoretic device

Abstract

An injection system including a first electrical circuit for concentration of an analyte and a second electrical circuit for injection of the concentrated analyte into an electrophoretic device is described, as well as methods of using the injection system.

1 . A method of injecting analyte, comprising:
 a) providing a system, the system comprising   a first electrical circuit including a first electrode, a second electrode, and an interruptible electrical communication between the first electrode and the second electrode,   a second electrical circuit including the first electrode, a third electrode, and an interruptible electrical communication between the first electrode and the third electrode,   an electrophoretic device including an electrophoretic channel, the electrophoretic channel including a sample injection end having a sample injection opening, and a second end opposite the sample injection end, and   a sample well, wherein the second electrode is disposed in the sample well, wherein   the first electrode is disposed adjacent and outside the electrophoretic channel, the second electrode is disposed adjacent the sample injection opening, and the third electrode is disposed adjacent the second end of the electrophoretic channel;   b) introducing analyte solution to the sample well;   c) supplying a voltage to the first electrical circuit to provide a voltage differential between the first electrode and the second electrode for a period of time sufficient to concentrate analyte from the analyte solution at or near the second electrode; and   d) interrupting the first electrical circuit and supplying a voltage to the second electrical circuit to provide a voltage differential between the first electrode and the third electrode for a period time sufficient to inject the concentrated analyte into the sample injection opening of the electrophoretic device.   
     
     
         2 . A method of injecting analyte, comprising:
 a) introducing an analyte solution to a sample well;   b) contacting the analyte solution with the first circuit of a system, the system comprising   a first electrical circuit including a first electrode, a second electrode, and an interruptible electrical communication between the first electrode and the second electrode;   a second electrical circuit including the first electrode, a third electrode, and an interruptible electrical communication between the first electrode and the third electrode; and   an electrophoretic device including an electrophoretic channel, the electrophoretic channel including a sample injection end having a sample injection opening, and a second end opposite the sample injection end, wherein   the first electrode is disposed adjacent and outside the electrophoretic channel, the second electrode is disposed adjacent the sample injection opening, and the third electrode is disposed adjacent the second end of the electrophoretic channel, wherein the analyte solution is in contact with at least the first electrode, the second electrode, and the sample injection opening;   c) supplying a voltage differential across the first circuit to form concentrated analyte from the analyte solution at or near the second electrode; and   d) supplying a voltage differential across the second circuit to inject the concentrated analyte through the sample injection opening and toward the third electrode.   
     
     
         3 . The method of  claim 2 , wherein the electrophoretic device and the sample well are affixed to a common substrate and are in fluid communication with each other. 
     
     
         4 . The method of  claim 3 , wherein the voltage differential across the first circuit is supplied for the period of time of about 30 seconds or less. 
     
     
         5 . The method of  claim 2 , wherein the voltage differential across the first circuit is interrupted while the voltage differential across the second circuit is supplied. 
     
     
         6 . The method of  claim 2 , wherein the voltage differential supplied across the first circuit is about 5V or less. 
     
     
         7 . The method of  claim 2 , wherein the voltage differential supplied across the second circuit is about 1000V or more. 
     
     
         8 . The method of  claim 2 , wherein the second circuit further includes the second electrode and an interruptible electrical communication between the second electrode and the third electrode. 
     
     
         9 . A method comprising:
 contacting a fluid sample with an entrance opening of an electrophoretic separation capillary, the fluid sample being disposed in a container and including at least one target component;   providing an electric field that concentrates the at least one target component at or near the entrance opening to form a concentrated target component; and   providing an electric field that injects the concentrated target component into the electrophoretic separation capillary through the entrance opening.