Ion exchange chromatography of carboxylic acids by indicator development

Abstract

A method for the detection of carboxylate ions in the effluent from the ion exchange chromatographic column was established. Sodium chloride solutions containing either hydrochloric acid, sodium hydroxide or cationic buffer such as diethylenetriamine were used as eluents. The effluent from the chromatographic column was successively led to a “buffer apprehending column” to remove cationic components of the buffers and to bring the pH to almost neutral. The effluent from the latter column was mixed with a bromophenol blue solution, and then the transmittance at 570 mμ was measured with automatic recordings.
Anion exchange resin, Dowex 1 × 8 chloride, was used for the chromatographic column, and cation exchange resin, Amberlite XE-64 and Dowex 50W × 8, were used for the buffer apprehending column.
About 10^-6 mole of carboxylate ion was detected. Quantitative determination was not successful, however, because of non-linearity in color development and instability of the indicator solution.