A continuous electrochemical pump comprising a water generator compartment, an anode compartment on one side of said generator compartment, a cation exchange barrier, separating the generator compartment from the anode compartment, it first electrode in electrical communication with the anode compartment, a cathode compartment adjacent the generator chamber, an anion exchange barrier, separating the generation compartment from the cathode compartment, and a second electrode in electrical communication with the cathode compartment. Use of the pump as a sample concentrator. A feedback loop for the pump. A reservoir, with or without an intermediate piston, on the output side of the pump.