Patent ID: 6576896
Filing Date: 2003-06-10
Classification: B01L,G01N,H01J

Abstract:
A method for generating a solvent gradient, comprising:(a) providing a fluid path from a fluidic device to a counterelectrode, wherein the device comprises a plurality of reservoirs each containing a liquid, a fluid exit for directing liquid to the counterelectrode, wherein each reservoir is connected by a channel to a common channel for conducting liquid from each reservoir to the fluid exit, and wherein each reservoir further comprises an electrode in electrical contact with the liquid in the reservoir; (b) applying a first voltage to the counterelectrode; (c) applying a second voltage to a first electrode in a first reservoir to generate a difference in potential between the first electrode and the counterelectrode, wherein the difference in potential causes migration of a first liquid from the first reservoir to the common channel; (d) applying a third voltage to a second electrode in a second reservoir to generate a difference in potential between the second electrode and the counterelectrode, wherein the difference in potential causes migration of a second liquid from the second reservoir to the common channel, wherein the first and second liquids are combined in the common channel to provide a solvent gradient comprising a combination of the first and second liquids; and (e) wherein applying voltages to the first and second electrodes comprises: (i) applying an initial constant voltage to the first electrode and an initial constant slightly lower voltage to the second electrode; (ii) ramping the initial voltage applied to the second electrode to about the initial voltage applied to the first electrode and holding the second electrode constant at that voltage; and (iii) ramping the initial voltage applied to the first electrode to about the initial voltage applied to the second electrode and holding the first electrode constant at that voltage.