Ion exchange with conductivity suppression

This secondary column effectively converts ions due to the background electrolyte to a molecular species of limited ionisation leaving only the species of analytical interest as the major conducting species in deionised water. 

Separation of sample components occurs in analytical column 

The eluant then passes directly to a conductivity cell, where the analyte ions can be monitored in a background of deionised water, thus allowing quantitative determination from measurement of peak height or area. 

For anion analysis the suppressor is in the form of an acid ion exchanger. The bicarbonate or carbonate anions typical in eluants for anion analysis are converted to carbonic acid. 

The utility of ion suppression techniques in the analysis of ionisable molecules by reverse phase chromatography is limited to samples of weakly basic or acidic compounds. The analysis of stronger acids (pATj 3) or stronger bases (pA j, 8) would require eluant of pH, 2 or 8, respectively. Reverse phase chromatography with chemically bonded stationary phases is, however, restricted to eluant pH 2 and 8 for reasons previously discussed. 

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