Patent ID: 6685813
Filing Date: 2004-02-03
Classification: B01L,C07K,G01N

Abstract:
A method of separating components having a given negative or positive charge and contained in a sample, comprising(a) loading a separation microchannel having, in an upstream to downstream direction, an upstream end, an upstream channel region, a sample-volume channel region, a downstream separation channel region, and a downstream end, so as to fill (i) the upstream channel region with a trailing-edge electrolyte containing a trailing edge ion having an electrophoretic mobility lower than that of any of the sample components, and containing a selected concentration of a titratable species, (ii) the sample-volume channel region with the dilute sample, and (iii) the separation channel region with a leading-edge electrolyte, containing a leading edge ion having an electrophoretic mobility greater than that of any of the sample components; and (b) creating an electrical field potential across said microchannel, by applying a voltage potential across electrodes in contact with said upstream and downstream channel ends, thereby causing charged components in said sample to stack by isotachophoresis, and subsequently causing hydroxyl or hydrogen ions to migrate into the trailing-edge electrolyte, titrating said titratable species therein, under conditions that permit the sample to stack into a relatively small sample volume before hydroxyl- or hydrogen-ion migration into and through the sample-volume region is effective to overtake the charged sample components, wherein continued application of an electric potential across the channel ends causes charged sample components in the stacked sample volume to separate by zone electrophoresis.