Ion Chromatography for Inorganic Ions

Specialized ion exchangers have been developed for determination of inorganic ions with conductivity detection. The original system consisted of a separation column that separated the ions and a suppressor column (now a suppressor membrane) that converted the ions into highly conducting species at the same time as the conductivity of the eluent was reduced. 

On a cation exchanger, analyte cations are separated and eluted with 1-10 mM HCl. The eluted cations are released as highly conducting hydroxides, while the anions are retained on the membrane. 

Anions on an anion exchanger are separated and eluted with 2 mM carbonate or bicarbonate solutions, replacing the cations with protons on the suppressor, forming carbonic acid (with low conductance). 

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