Novel way of separating polyfluorocarboxylic acids by ion-exclusion chromatography

ion-exclusion chromatography has been successfully applied to the separatio n of a number of polyfluorocarboxylic acids. The separation of various mono - and dibasic polyfluorocarboxylic acids having a different alkyl group was investigated using a polymethacrylate-based weakly acidic cation-exchange resin (TSK gel OApak-A) in the H+-form and conductimetric detection. When w ater was used as the eluent, polyfluorocarboxylic acids could not be resolv ed. When an aqueous solution of sulfuric acid, benzoic acid, o-phthalic aci d, 1,3,5-benzenetricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, an d tartaric acid was used, the separation of polyfluorocarboxylic acids occu rred for monobasic ones. While, for fluorine-containing dibasic acids, impe rfect separation of peaks occurred. In order to improve their separation, t he effect of an addition of organic modifiers such as methanol, 2,3,2-trifl uoroethanol and 2H-hexafluoro-2-propanol in the eluent was also investigate d. (C) 2000 Elsevier Science B.V. All rights reserved.