Ion-exchange treatment of complicated samples prior to ion chromatographic analysis

Abstract

Samples that are treated in a manner which results in a high concentration of electrolyte (carbonate fusion, for example) generally cannot be analysed directly by ion chromatography using a conductivity detector. The common practice of diluting the dissolved residue prior to injection into the chromatograph is not appropriate when the analytes are at trace levels. In this paper the use of a dual ion-exchange method to decrease the electrolyte concentration is described. The method is illustrated with reference to coal, polymer and citrus leaf samples and is compared with the use of direct addition of resin beads to the dissolved products of carbonate fusions. Also described is the sequential use of Donnan dialysis into a carbonate solution and dual ion exchange to pre-treat samples that contain high concentrations of either suspended solids or neutral solutes. Following such pre-treatment, trace amounts of anions in turbid water and in syrup are determined by ion chromatography