Development of packed-column suppressor system for capillary ion chromatography and its application to environmental waters

A novel suppressor unit for capillary ion chromatography was designed to reduce the background conductivity and at the same time to increase the analyte signal. Regeneration of the suppressor was carried out on-line by passing an appropriate acidic solution through the column to displace the accumulated eluent cations. By using two 6-port microswitching valves and two packed capillary column suppressors, the background conductivity of sodium carbonate–bicarbonate mobile phase was maintained at low conductivity for continuous chromatographic runs, and the detection limits at low ppb levels were achieved. The relative standard deviations (RSDs) for the retention time, peak area and peak height of six common inorganic anions (0.05 mM each of F−, Cl−, NO2−, Br−, NO3− and SO42−) were between 0.5–0.9, 1.1–4.6 and 0.7–4.9%, respectively. The present system was successfully applied to the determination of inorganic anions in river water and tap water samples.