Separation of Dissolved Aluminum in Neutral/Slightly Basic River Water by Cation-Exchange Chromatography with Fluorometric Detection of the Lumogallion–Aluminum Complex

Abstract

Abstract The separation of dissolved aluminum in neutral/slightly basic river (Seta River) water was carried out using high-performance cation-exchange chromatography with a gradient elution of calcium ion in a dilute nitric acid solution (pH 4) and fluorometric detection of the lumogallion–aluminum complex. Although three peaks may appear, which correspond to species having a charge of less than +1, +2 and +3, only one major peak at the “3+” position appeared. From the sample pH and this result of separation, the main species of dissolved aluminum was concluded to be Al(OH)4−. In order to evaluate whether the elution was complete or not, the peak areas obtained with and without the cation-exchange column were compared. For an accurate evaluation of the elution peak, the residual solution of the solvent extraction with the 8-quinolinol/chloroform system was used. The elution of dissolved aluminum from the cation-exchange column was found to be incomplete (or not quantitative); i.e., the percentage of eluted aluminum was 79 and 70% for two Seta River water samples in October and January, respectively. The chemical form of the aluminum species which was adsorbed in the cation-exchange column is discussed.