An apparatus for suppressing an eluent of an aqueous sample stream including analyte ions of one charge, positive or negative, the apparatus comprising: a primary channel member including a primary channel extending through the primary channel member, the primary channel member having an inlet port and an outlet port, wherein the primary channel member is configured for the eluent to flow from the inlet port, through the primary channel, and then to the outlet port; a first block disposed on a first side of the primary channel member and including a first surface that faces the primary channel, wherein the first surface at least partly defines a first regenerant flow channel, the first regenerant flow channel including a first inlet port and a first outlet port; a first charged barrier configured to pass ions of only one charge, positive or negative, and of blocking bulk liquid flow, the first charged barrier disposed between the primary channel member and the first block; a second block disposed on a second side of the primary channel member and including a second surface that faces the primary channel, wherein the second surface at least partly defines a second regenerant flow channel, the second regenerant flow channel including a second inlet port and a second outlet port; a second charged barrier configured to pass ions of only one charge, positive or negative, and of blocking bulk liquid flow, the second charged barrier disposed between the primary channel member and the second block, wherein the first charged barrier and the second charged barrier have the same charge polarity; and a first electrode and a second electrode disposed in the first regenerant channel and the second regenerant channel, respectively; characterised by a first stationary flow-through ion exchange material disposed in the primary channel; the first stationary flow-through ion exchange material comprising a polyolefin substrate having a functional polymer layer disposed thereon, preferably the polyolefin comprises polyethylene, preferably the functional polymer layer comprises a first portion with strong ionizable groups and a second portion with weak ionizable groups; preferably the first stationary flow-through ion exchange material comprises a screen; wherein the polyolefin substrate has a pore structure with a pore size ranging from about 5 microns to about 250 microns; the functional polymer layer having a thickness ranging from about 1 micron to about 20 microns, and a layer pore structure having a pore size ranging from about 1 nm to about 100 nm; and the functional polymer layer comprises an ion exchange layer. a primary channel member including a primary channel extending through the primary channel member, the primary channel member having an inlet port and an outlet port, wherein the primary channel member is configured for the eluent to flow from the inlet port, through the primary channel, and then to the outlet port; a first block disposed on a first side of the primary channel member and including a first surface that faces the primary channel, wherein the first surface at least partly defines a first regenerant flow channel, the first regenerant flow channel including a first inlet port and a first outlet port; a first charged barrier configured to pass ions of only one charge, positive or negative, and of blocking bulk liquid flow, the first charged barrier disposed between the primary channel member and the first block; a second block disposed on a second side of the primary channel member and including a second surface that faces the primary channel, wherein the second surface at least partly defines a second regenerant flow channel, the second regenerant flow channel including a second inlet port and a second outlet port; a second charged barrier configured to pass ions of only one charge, positive or negative, and of blocking bulk liquid flow, the second charged barrier disposed between the primary channel member and the second block, wherein the first charged barrier and the second charged barrier have the same charge polarity; and a first electrode and a second electrode disposed in the first regenerant channel and the second regenerant channel, respectively; characterised by a first stationary flow-through ion exchange material disposed in the primary channel; the first stationary flow-through ion exchange material comprising a polyolefin substrate having a functional polymer layer disposed thereon, preferably the polyolefin comprises polyethylene, preferably the functional polymer layer comprises a first portion with strong ionizable groups and a second portion with weak ionizable groups; preferably the first stationary flow-through ion exchange material comprises a screen; wherein the polyolefin substrate has a pore structure with a pore size ranging from about 5 microns to about 250 microns; the functional polymer layer having a thickness ranging from about 1 micron to about 20 microns, and a layer pore structure having a pore size ranging from about 1 nm to about 100 nm; and the functional polymer layer comprises an ion exchange layer.