[Homer Jay]

In ion chromatography the eluent is a NaHCO3 / Na2CO3 buffer solution. The suppressor replaces all Na+ from the eluent with H+. If there is NaCl in the sample it also replaces those Na+, so there is more H+ in the mobile phase than HCO3-. H+ won't be absorbed by the hydrogen carbonate anymore, but the conductivity of H+ is the biggest. So why is H+ in excess not spoiling the conductivity-measurement of the analysis?

[kevins]

We can imagine the flow in the IC tubing and in the column is "plug" flow. When the carbonate and chloride containing solution flow through the suppressor, the H+ will exchange the Na+ along the narrow tubing therefore the carbonate to form a less conductivty carbonic acid and the chloride to form high conductivity HCl.