Abstract: Apparatus and method for chromatographic separation and quantitation of different ions of like charges in a sample, e.g., cations or anions. Referring to anion separation, the sample is directed to a first chromatographic column of the ion exclusion type in which the weak acids (e.g., carboxylic acids) and their salts are partially or totally resolved and separated from a fraction of strong acids (e.g., mineral acids) due to Donnan exclusion. The resolved weak acids may be passed directly to a conductivity cell for quantitative detection. The strong acids may be directed to anion exchange bed with a highly ionized developing reagent and eluted in resolved form with the effluent being passed to a suppressor ion exchange bed wherein the developing reagent is converted to a weakly ionized form without destroying the anion separation. Then, a fraction of the strong acids is detected with the same or a different conductivity cell.

Abstract: Method and apparatus for quantitative analysis of weakly ionized anions (e.g. carboxylates) or cations (e.g., organic amines). For anion analysis, the sample and a strong acid (e.g., HCl) eluent are passed through an ion exclusion chromatography column (cation exchange resin) to resolve the weak anions while eluting the strong anions in the void volume peak. HCl is stripped on an ion exchange stripper column in the silver ion form and the effluent is directed through a conductivity cell and associated readout for detection. For weak cation analysis, the sample and a strong base (e.g., Ba(OH).sub.2) eluent are passed through an ion exclusion chromatography column (anion exchange resin) to resolve the weak cations while eluting the strong cations (e.g., Na.sup.+, K.sup.+) in the void volume peak. Ba(OH).sub.2 is stripped on an ion exchange stripper column in the sulfate ion form and the effluent is directed through a conductivity cell and associated readout for detection.