Dionex Corporation

The Dow Chemical Company

John R Stillian

Christopher A Pohl

Keith A Friedman

Roy D Rocklin

Steven B Rabin

Victor M Barreto

Mahmood Toofan

Archava Siriraks

Nebojsa Avdalovic

Purnendu K Dasgupta

Neboisa Avdalovic

Ryszard Gajek

Douglas L Strong

Roseanne W Slingsby

A system for pretreating sample streams including a concentrated matrix compound to neutralize the compound. The system includes an electrochemical membrane device in which sample flows through a sample flow channel of the device separated from a matrix ion receiving flow channel by an ion exchange membrane preferentially permeable to ions of the opposite charge to the ions to be analyzed. The ionic species in the thus-pretreated sample are directed to an analytical system such as an ion chromatograph.

Electrochemical pretreatment system for liquid sample analysis

Apparatus and methods are provided for increasing the sensitivity of detection of ionic species separated by capillary electrophoresis. The apparatus includes capillary electrophoretic separating means, suppressor means and detector means.

Method and apparatus for improved detection of ionic species by

A method of streamlining and lowering the cost of operation of ion chromatography as well as improving detection limits is disclosed. The apparatus includes chromatographic separating means through which a sample is eluted in an eluent solution including an electrolyte. The apparatus includes suppressor means having a chromatography effluent compartment means separated from a detector effluent compartment means by an ion exchange membrane, forming a chromatography effluent flow channel and a detector effluent channel, respectively. Electrode means are disposed in communication with both flow channels for passing an electric current transverse to the solution that is passing through them. The chromatography effluent flows through the chromatography effluent flow channel of the suppressor and through detector means which detects resolved ionic species therein. The effluent from the detector means is then recycled through the detector effluent flow channel and forms a sump for electrolyte ions passing across the chromatography effluent as well as supplying the water for the electrolysis reaction generating acid (or base) for suppression.

Ion chromatography system using electrochemical suppression and detector

A method and apparatus has been provided for generating a high purity aqueous stream with selected ionic species--either cation (e.g. sodium) or anion (e.g. sulfate) and suitable for use as a chromatography eluent. In one form, an eluent generating means defines a source channel and a product channel separated by a permselective ion exchange membrane including exchangeable ions of the same charge as the selected ionic species. The membrane allows passage of ions of the same charge as the ionic species but is resistant to transmembrane passage of ions of opposite charge. Means is provided for applying an electrical potential between the source channel and product channel. In another form of the device, two different membranes define two source channels, a positively charged, anode source channel and a negatively charged cathode source channel, and a product channel. The effluent from the product channel is directed to the chromatographic separation means. Means is also provided for supplying liquid sample to the chromatographic separation means.

Method and apparatus for generating a high purity chromatography eluent

A suppressor for use in ion chromatography including at least an effluent flow channel separated by a charged membrane from a suppressor flow channel. A screen of the same charge as the membrane is placed in at least the effluent flow channel. Preferably, a similar screen is placed in the regenerant flow channel. The screen increases the dynamic capacity of the membrane suppressor.

Modified membrane suppressor and method for use

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Pleasanton, CA, United States of America

John R Stillian