Abstract: The current invention is an apparatus for concentrating ions in a water stream and a method for using the apparatus to concentrate ions for detection and/or removal. The apparatus is comprised of an electrically charged barrier, a distal electrode having an electrical charge with a sign opposite to the electrical charge of the barrier, and a proximate electrode having an electrical charge with a sign corresponding to the electrical charge of the barrier. The apparatus further includes a moving water stream which is processed to comprise an ion-depleted stream and an ion-concentrated stream located between the distal electrode and the first surface, a first diversion structure to divert the ion-concentrated stream, a second diversion structure to divert the ion-depleted stream, and an electrical power source operatively coupled with the distal and proximate electrodes.