Electrochemically driven pump
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.
1. A continuous electrochemical concentrator in an analytical system comprising:
(a) a water generator compartment having an outlet,
(b) an anode compartment disposed adjacent one side of said generator compartment,
(c) a cation exchange barrier separating said generator compartment from said anode compartment, said cation exchange barrier being capable of passing cations but not anions and of blocking bulk liquid flow,
(d) a first electrode in electrical communication with said anode compartment,
(e) a cathode compartment disposed adjacent said generator chamber,
(f) an anion exchange barrier separating said generation compartment from said cathode compartment, said anion exchange barrier being capable of passing anions but not cations and of blocking bulk liquid flow,
(g) a second electrode in electrical communication with said cathode compartment, and
(h) a detector in fluid communication with said water generator compartment outlet in the absence of a sample injector for the supply of sample, other than sample supplied from said water generator compartment outlet, disposed between said generator compartment outlet and said detector.
2. The concentrator of claim 1 further comprising reservoirs of sample water in said anode and cathode compartments.
3. A method for concentrating and detecting analyte anions and cations in a water sample using a concentrator comprising an aqueous liquid generator compartment having an outlet; an anode compartment containing a first portion of said analyte anion- and cation-containing water sample and disposed adjacent to said generator compartment; a cation exchange barrier separating said generator compartment from said anode compartment; said cation exchange barrier being capable of passing cations but not anions and of blocking bulk liquid flow, a first electrode in electrical communication with said anode compartment; a cathode compartment containing a second portion of said analyte anion- and cation-containing water sample and adjacent to said generator chamber; an anion exchange barrier separating said generator compartment from said cathode compartment; said anion exchange barrier being capable of passing anions but not cations and of blocking bulk liquid flow, and a second electrode in electrical communication with said cathode compartment, said method comprising:
(a) passing an electric current between said first and second electrodes through said first and second water sample portions in said anode and cathode compartments, and through said cation and anion exchange membranes, to generate hydroxide ions in said cathode compartment and hydronium ions in said anode compartment,
(b) passing said generated hydroxide ions and analyte anions in said water sample through said anion exchange barrier and said generated hydronium ions and analyte cation in said water sample through said cation exchange barrier into said generator compartment to electrochemically generate a water product sample including said passed analyte cations and anions, and
(c) flowing said generated water product sample in a stream out of said generator compartment to a detector to detect said analyte cations and anions in said water product sample in the absence of the injection of any additional sample between said generator compartment and said detector.
4. The method of claim 3 in which the cation exchange barrier includes exchangeable ions predominantly in the hydronium ion form and the anion exchange barrier includes exchangeable ions predominantly in the hydroxide ion form.