 Intermittent electrolytic packed bed suppressor regeneration for ion chromatography |
| The present invention relates to ion chromatography using electrochemical regeneration of a packed ... |
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| Ion chromatography using frequent regeneration of batch-type suppressor |
| In accordance with the invention, ion chromatography methods and apparatus are provided using a ... |
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| Intermittent electrolytic packed bed suppressor regeneration for ion chromatography |
| The present invention relates to ion chromatography using electrochemical regeneration of a packed ... |
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Method and apparatus for ion analysis and detection using reverse mode suppression
| Details |
Inventors: Pohl, Christopher A.; Slingsby, Rosanne W.; Johnson, Edward L.; Angers, Leilani;
Assignee: Dionex Corporation (Sunnyvale, CA)
Primary Examiner: Adee; John
Assistant Examiner:
Attorney, Agent or Firm: Flehr, Hohbach, Test, Albritton & Herbert
a method of ion analysis and detection of weakly dissociated anions or cations in an eluent by first separating such ions on a chromatographic separation medium by ion exclusion chromatography or mobile phase ion exclusion chromatography. The eluent include an acid or base with a co-ion of the same charge as the ions to be separated, such co-ions being in the hydronium or hydroxide form. In one embodiment the effluent from the separation medium is contacted with one side of an ion-exchange membrane having exchangeable ions of opposite charge to the ionic species. The opposite side of the membrane includes a regenerant with salt-forming suppression ions capable of forming a weakly conducting salt with the co-ions. Then the separated ionic species are detected preferably by a conductivity detector. In another embodiment, the membrane is replaced by a resin bed with ion-exchanging sites of opposite charge to the co-ions. There, co-ions form a suppressed salt with the exchangeable ions. |
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The system of the present invention is useful for determining a large number of weak ionic species so long as the species to be determined are solely anions or solely cations.
A suitable sample includes surface waters, and other liquids such as industrial chemical waste, body fluids, beverages such as fruits and wines, and drinking water.
When the term "ionic species" is used herein, it includes species in ionic form and components of molecules which are ionizable under the conditions of the present system.
Referring to FIG.
1, a simplified apparatus for performing the present invention is illustrated.
The system includes chromatographic separation means 10 including a chromatographic separation medium.
The chromatographic separation medium is of a type capable of separating the weakly dissociated anions or cations by ion exclusion chromatography.
In the IEC embodiment, such resin includes permanently attached ion exchanging site with exchangeable ions of opposite charge to the weak ionic species so that chromatographic separation is performed by selective temporary retention on the column.
In the MPIEC embodiment, the chromatographic separation medium is of a type conventionally employed for MPIC as described in detail in U.
S.
Pat.
No.
4,265,634, even though the technique of separation is substantially different as set forth in detail below.
Briefly summarized, such chromatographic separation medium includes a porous hydrophobic chromatographic medium, preferably a resin bed, with essentially no permanently attached ion-exchanging sites.
Arranged in series with column 10 is suppressor means 11 for suppressing the conductivity of the electrolyte of the eluent but not the conductivity of the separated ions.
The effluent from suppressor means 11 is directed to a detector for detecting the resolved ionic species therefrom, preferably in the form of a flow-through conductivity cell 12.
A suitable sample is supplied to sample injection valve 13 which is swept through the apparatus by the solution of eluent from eluent reservoir 14 drawn by pump 15, and then passed through the sample injection valve 13
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