An electrolytic reagent concentrator device comprising: a reagent ion source channel ; a counterion source channel ; a regenerant concentration channel ; a first ion exchange barrier having a first charge and being permeable to at least a reagent ion having a charge of opposite polarity to the first charge, but not to other ions having a charge of a same polarity as the first charge, wherein the first ion exchange barrier separates the reagent ion source channel from the regenerant concentration channel by blocking a bulk flow of a liquid between the reagent ion source channel and the regenerant concentration channel ; a second ion exchange barrier having a second charge opposite in polarity to the first charge and being permeable to at least an electrolytically generated counterion having a charge of opposite polarity to the second charge, but not to other ions having a charge of a same polarity as the second charge, wherein the second ion exchange barrier separates the counterion source channel from the regenerant concentration channel by blocking the bulk flow of the liquid between the counterion source channel and the regenerant concentration channel ; an electrode in electrical communication with the reagent ion source channel ; a counterelectrode in electrical communication with the counterion source channel ; and a flow control device for restricting a flow rate of the liquid into the regenerant concentration channel in comparison to a flow rate of the liquid containing the reagent ion into the reagent ion source channel ; wherein the electrode , the reagent ion source channel , the regenerant concentration channel , the counterion source channel , and the counterelectrode form an electrolytic cell so as to, upon application of an electrolytic potential or current, drive reagent ions from the reagent ion source channel and electrolytically generated counterions from the counterion source channel into the regenerant concentration channel . a reagent ion source channel ; a counterion source channel ; a regenerant concentration channel ; a first ion exchange barrier having a first charge and being permeable to at least a reagent ion having a charge of opposite polarity to the first charge, but not to other ions having a charge of a same polarity as the first charge, wherein the first ion exchange barrier separates the reagent ion source channel from the regenerant concentration channel by blocking a bulk flow of a liquid between the reagent ion source channel and the regenerant concentration channel ; a second ion exchange barrier having a second charge opposite in polarity to the first charge and being permeable to at least an electrolytically generated counterion having a charge of opposite polarity to the second charge, but not to other ions having a charge of a same polarity as the second charge, wherein the second ion exchange barrier separates the counterion source channel from the regenerant concentration channel by blocking the bulk flow of the liquid between the counterion source channel and the regenerant concentration channel ; an electrode in electrical communication with the reagent ion source channel ; a counterelectrode in electrical communication with the counterion source channel ; and a flow control device for restricting a flow rate of the liquid into the regenerant concentration channel in comparison to a flow rate of the liquid containing the reagent ion into the reagent ion source channel ; wherein the electrode , the reagent ion source channel , the regenerant concentration channel , the counterion source channel , and the counterelectrode form an electrolytic cell so as to, upon application of an electrolytic potential or current, drive reagent ions from the reagent ion source channel and electrolytically generated counterions from the counterion source channel into the regenerant concentration channel . <EOS>