Suppressor for continuous electrochemically suppressed ion chromatography and method

Abstract

Methods and devices for continuous electrochemically suppressed ion chromatography are disclosed. In preferred aspect of the invention, a chromatography effluent comprising analyte ions and electrolyte is split into a first chromatography effluent flow stream and a second chromatography effluent flow stream. Electrolysis ions selected from the group consisting of hydronium ions and hydroxide ions are generated by the electrolysis of water. Electrolysis ions of the same charge as the electrolyte and the second chromatography effluent stream are flowed through a stationary phase thereby suppressing the electrolyte in the second chromatography effluent flow stream. The analyte ions are subsequently detected in the suppressed second chromatography effluent flow stream.

We claim:  
     
         1 . A method of continuous electrochemically suppressed ion chromatography comprising: 
 (a) chromatographically separating analyte ions in an aqueous mobile phase comprising electrolyte to form an aqueous chromatography effluent comprising separated analyte ions and electrolyte;    (b) splitting the chromatography effluent into a first chromatography effluent flow stream and a second chromatography effluent flow stream;    (c) generating electrolysis ions selected from the group consisting of hydronium ions and hydroxide ions by performing electrolysis of water;    (d) flowing the second chromatography effluent stream through a stationary phase comprising ion-exchange resin during step (c); and    (e) detecting the separated analyte anions in the suppressed second chromatography effluent stream.    
     
     
         2 . The method of  claim 1  wherein the analyte ions comprise anions, the electrolyte comprises cations and the electrolysis ions comprise hydronium ions.  
     
     
         3 . The method of  claim 1  wherein the analyte ions comprise cations, the electrolyte comprises anions and the electrolysis ions comprise hydroxide ions.  
     
     
         4 . The method of  claim 1  wherein the stationary phase remains substantially in its unexhausted form during step (d).  
     
     
         5 . The method of  claim 4  wherein the stationary phase comprises cation exchange resin in the hydronium form.  
     
     
         6 . The method of  claim 4  wherein the stationary phase comprises anion exchange resin in the hydroxide form.  
     
     
         7 . The method of  claim 1  wherein steps (d) and (e) are performed substantially simultaneously.  
     
     
         8 . A method of continuous electrochemically suppressed ion chromatography comprising: 
 (a) chromatographically separating analyte ions in a mobile phase comprising electrolyte to form a chromatography effluent comprising separated analyte ions and electrolyte;    (b) splitting the chromatography effluent into a first chromatography effluent stream and a second chromatography effluent stream;    (c) flowing the first chromatography effluent stream through a first stationary phase comprising ion exchange resin and flowing the second chromatography effluent stream through a second stationary phase comprising ion exchange resin;    (d) generating electrolysis ions selected from the group consisting of hydronium ions and hydroxide ions during step (c) by performing electrolysis on water;    (e) simultaneously flowing the second chromatography effluent stream and the electrolysis ions that are of the same charge as the electrolyte through the second stationary phase during step (d) thereby driving the electrolyte away from the second chromatography effluent stream and into the first chromatography effluent stream; and    (f) detecting the separated analyte ions in the second chromatography effluent stream.    
     
     
         9 . The method of  claim 8  wherein the analyte comprise anions, and in step (e) the electrolyte comprises cations and the electrolysis ions comprise hydronium ions.  
     
     
         10 . The method of  claim 8  wherein the analyte ions comprise cations, and in step (e) the electrolyte comprises anions and the electrolysis ions comprise hydroxide ions.  
     
     
         11 . The method of  claim 8  wherein the second stationary phase remains substantially in its unexhausted form during step (e).  
     
     
         12 . The method of  claim 11  wherein the second stationary phase comprises cation exchange resin in its hydronium form.  
     
     
         13 . The method of  claim 11  wherein the second stationary phase comprises anion exchange resin in its hydroxide form.  
     
     
         14 . The method of  claim 8  wherein gas by-products of the electrolysis are removed from the second chromatography effluent stream prior to detecting the analyte ions in step (f).  
     
     
         15 . The method of  claim 8  wherein the electrolyte in the first chromatography effluent stream is removed and the first chromatography effluent stream is reused as a mobile phase for carrying analyte ions in a subsequent analysis run.  
     
     
         16 . The method of  claim 8  wherein steps (e) and (f) are performed substantially simultaneously.  
     
     
         17 . The method of  claim 8  wherein the source of water for the electrolysis is the chromatography effluent.  
     
     
         18 . A suppressor adapted for use in a method of continuous electrochemically suppressed ion chromatography, the suppressor comprising: 
 (a) an inlet, a first outlet, a second outlet and a third outlet;    (b) a first stationary phase comprising ion exchange resin positioned in the path of fluid flow through the suppressor from the inlet to the third outlet;    (c) a second stationary phase comprising ion exchange resin positioned in the path of fluid flow through the housing from the inlet to the first outlet; and    (d) a first regeneration electrode positioned at the third outlet and a second regeneration electrode positioned at the second outlet.    
     
     
         19 . The suppressor of  claim 18  wherein the first and second stationary phases comprise free ion exchange resin.  
     
     
         20 . The suppressor of  claim 18  wherein the first and second stationary phases comprise ion exchange resin encapsulated in a membrane.  
     
     
         21 . The suppressor of  claim 18  further comprising sensor electrodes positioned in the second stationary phase.  
     
     
         22 . A system for continuous electrochemically suppressed ion chromatography, the system comprising: 
 (a) a mobile phase source;    (b) a pump;    (c) a sample injector;    (d) a chromatography column in liquid communication with the mobile phase source and sample injector;    (e) a suppressor in liquid communication with the chromatography column, the suppressor comprising an inlet for receiving chromatography effluent, a first outlet, a second outlet, and a third outlet, a first regeneration electrode positioned at the third outlet and a second regeneration electrode positioned at the second outlet, a first stationary phase comprising ion exchange resin located in the path of fluid flow from the inlet to the third outlet, a second stationary phase comprising ion exchange resin located in the path of fluid flow from the inlet to the first outlet;    (f) a power source in electrical communication with the first and second regeneration electrodes; and    (g) a detector in liquid communication with the first outlet of the suppressor.    
     
     
         23 . The system of  claim 22  wherein the first and second stationary phase comprise free ion exchange resin.  
     
     
         24 . The system of  claim 22  wherein the first and second stationary phases comprise ion exchange resin encapsulated in a membrane.  
     
     
         25 . The system of  claim 22  further comprising a gas permeable membrane in liquid communication with, and positioned between in the direction of liquid flow, the suppressor and the detector.  
     
     
         26 . The system of  claim 22  wherein the suppressor further comprises sensor electrodes positioned in the second stationary phase.  
     
     
         27 . A method of continuous electrochemically suppressed ion chromatography comprising: 
 (a) chromatographically separating analyte ions in an aqueous mobile phase comprising electrolyte to form an aqueous chromatography effluent comprising separated analyte ions and electrolyte;    (b) conducting electrolysis of water to generate the electrolysis ions selected from the group consisting of hydroxide ions and hydronium ions and flowing the electrolysis ions through a stationary phase positioned in the suppressor.    (c) during step (b) suppressing the electrolyte in the chromatography effluent by flowing the chromatography effluent through a first inlet of the suppressor and across at least a portion of the stationary phase;    (d) flowing the suppressed chromatography effluent through a first outlet of the suppressor to a detector and detecting the analyte ions in the suppressed chromatography effluent;    (e) flowing detector effluent to the suppressor through a second inlet; and    (f) flowing the detector effluent to waste through a second outlet in the suppressor.    
     
     
         28 . The method of  claim 27  wherein the stationary phase comprises free ion exchange resin.  
     
     
         29 . The method of  claim 27  wherein the stationary phase comprises ion exchange resin encapsulated in a membrane.  
     
     
         30 . A suppressor for use in continuous electrochemically suppressed ion chromatography, the suppressor comprising; 
 a first inlet, a first outlet and a second outlet;    a first stationary phase located in the path of fluid flow through the suppressor from the first inlet to the first outlet;    a second stationary phase located in the path of fluid flow through the suppressor from the first inlet to the second outlet;    a pair of regenerator electrodes wherein the first and second stationary phases are located between the electrodes such that an electrical potential may be applied across the first and second stationary phases;    wherein the first stationary phase and the second stationary phase comprise oppositely charged ion exchange resin.    
     
     
         31 . The suppressor  claim 30  wherein the first stationary phase comprises hydroxide ions and the second stationary phase comprises hydronium ions.  
     
     
         32 . The suppressor of  claim 31  wherein the stationary phase comprises free ion exchange resin.  
     
     
         33 . The suppressor of  claim 31  wherein the stationary phase comprises ion exchange resin encapsulated in a membrane.