Janet J Mcneill

US Patent:

43148239, Feb 9, 1982

Filed:

Sep 13, 1979

Appl. No.:

6/075260

Inventors:

William E. Rich - Mountain View CA
Frank C. Smith - Felton CA
Janet L. McNeill - Sunnyvale CA

Assignee:

Dionex Corporation - Sunnyvale CA

International Classification:

G01N 3104
G01N 3108

US Classification:

23230R

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. Prior to separation, the strong acids are preferably directed through a concentrator column formed of ion exchange resin in which they are retained but not resolved while the remaining solution is removed.