Electrolytic buffer generator

Abstract

Buffer generators are described based on electrodialytic devices. The methods of using these devices can generate buffers for diverse applications, including separations, e.g., HPLC and ion chromatography. Also provided are chromatographic devices including the buffer generators, generally located upstream from a chromatography column, sample injector valve or both.

1 . An electrodialytic method for generating a modified buffer solution, said method comprising:
 (a) flowing a buffer solution, including cations and anions, at a concentration greater than about 10 mM through a modified-buffer generation flow channel under a pressure less than about 30 psi;   (b) flowing an aqueous liquid stream through an ion-receiving flow channel separated from said modified-buffer flow channel by a first ion exchange barrier including exchangeable cations or anions, but not both, and capable of blocking bulk liquid flow, said membrane having a surface area greater than about 0.5 in 2 ; and   (c) passing a current between first and second electrodes across said modified-buffer flow generation channel and said ion-receiving flow channel to cause cations or anions, but not both, to be transported across said first ion exchange barrier to generate a modified buffer solution which exits from said modified-buffer generation flow channel.   
     
     
         2 . The method of  claim 1 , wherein said cations or anions are transported from said modified-buffer flow channel across said first ion exchange barrier into said ion-receiving channel. 
     
     
         3 . The method of  claim 1  further comprising:
 (d) flowing an aqueous liquid stream through a source channel for ions separated by a second ion exchange membrane from said modified-buffer flow channel, said second ion exchange membrane including exchangeable ions of the same charge, positive or negative, as the exchangeable ions of said first ion exchange membrane. 
 
     
     
         4 . The method of  claim 3 , in which said first electrode is disposed in said ion-receiving channel and said second electrode is disposed in said source channel. 
     
     
         5 . The method of  claim 3 , wherein said ions are a member selected from hydronium ions and hydroxide ions. 
     
     
         6 . The method of  claim 1  further comprising:
 (d) injecting a sample with analyte ions to be separated into said exiting modified buffer and separating said analytes; said buffer solution flowing to said modified-buffer flow channel not being previously generated by an electrolytic eluent generator. 
 
     
     
         7 . The method of  claim 3  wherein a member selected from cations and anions is transported from said modified-buffer channel into a member selected from said ion-receiving channel and said source channel. 
     
     
         8 . The method of  claim 1  further comprising:
 (d) outputting said modified buffer solution from said modified-buffer generation flow channel with a modified buffer concentration, in which a magnitude of said current is proportional to a change in a concentration of the flowed buffer solution. 
 
     
     
         9 . The method of  claim 1  wherein a member selected from cations and anions flows from said ion-receiving channel. 
     
     
         10 . The method of  claim 1  further comprising:
 (d) flowing an aqueous liquid stream through an electrode channel for ions separated by a bipolar membrane from said modified-buffer flow channel, said bipolar membrane configured to split water and generate hydronium ions and hydroxide ions, and also to block bulk liquid flow, said current passing between said first electrode disposed in said electrode chamber and said second electrode disposed in said ion-receiving channel via said modified-buffer flow generation channel. 
 
     
     
         11 . The method of  claim 10 , wherein said ions are a member selected from hydronium ions and hydroxide ions. 
     
     
         12 . An electrodialytic method for generating a modified buffer solution, said method comprising:
 (a) flowing a buffer solution, including cations and anions through a modified-buffer generation flow channel, wherein said modified-buffer generation flow channel is separated from a first ion-receiving chamber by an anion exchange membrane capable of blocking bulk liquid flow and wherein said modified-buffer generation flow channel is separated from a second ion-receiving chamber by a cation exchange membrane capable of blocking bulk liquid flow; and   (b) passing a current between first and second electrodes across said ion-receiving chamber to cause cations to be transported across a cation exchange membrane and to cause anions to be transported across an anion exchange membrane, wherein said first and second electrodes are disposed within said first and second ion-receiving chambers, respectively, and are separated from said modified-buffer flow channel, thereby generating a modified buffer solution which exits from said modified-buffer generation flow channel.   
     
     
         13 . The method of  claim 12  wherein said current is passed across said modified buffer flow generation channel from said first ion-receiving chamber to said second ion receiving chamber. 
     
     
         14 . The method of  claim 12  wherein a member selected from cations and anions is transported from said modified-buffer channel into a member selected from said first ion-receiving chamber and said second ion-receiving chamber. 
     
     
         15 . The method of  claim 12  wherein a member selected from cations and anions is transported into said modified-buffer channel from a member selected from said first ion-receiving chamber and said second ion-receiving chamber. 
     
     
         16 . The method of  claim 12  further comprising:
 (c) outputting said modified buffer solution from said modified-buffer generation flow channel with a modified buffer concentration, in which a magnitude of said current is proportional to a change in a concentration of the flowed buffer solution. 
 
     
     
         17 . The method of  claim 12  wherein a member selected from cations and anions flows from said ion-receiving chamber. 
     
     
         18 . The method of  claim 12  further comprising
 (c) injecting a sample with analyte ions to be separated into said exiting modified buffer and separating said analytes. 
 
     
     
         19 . The method of  claim 18  wherein said buffer solution flowing to said modified-buffer flow channel was not previously generated by an electrolytic eluent generator. 
     
     
         20 . An electrodialytic method for generating a modified buffer solution, said method comprising:
 (a) flowing an aqueous liquid stream through a modified-buffer generation flow channel;   (b) passing a current between first and second electrodes across said modified-buffer flow generation channel and a first ion-receiving chamber to cause cations or anions, but not both, to be transported across said first ion exchange barrier to generate a modified buffer solution which exits from said modified-buffer generation flow channel, said first ion-receiving chamber being separated from said modified-buffer flow channel by said first ion exchange barrier including exchangeable cations or anions, but not both, and capable of blocking bulk liquid flow.   
     
     
         21 .- 41 . (canceled)