Speciation of Aluminium in Environmental Water Samples Employing Microcolumn Chelating Ion-Exchange Chromatography - ETAAS

Abstract

A microcolumn chelating ion-exchange chromatography-electrothermal atomic absorption spectrometry procedure (ETAAS) was developed for aluminium speciation at the nanogram per millilitre level in water samples from the environment. Chelex-100 resin (100-200 mesh, H+ form) was filled into a micro column and connected to a peristaltic pump. Before analysis, the resin column was equilibrated to the pH of the particular sample analyzed. Sample was then pumped through the column at a flow rate of 0.5 cm3 min−1. Labile aluminium monomeric species were retained by the resin column and, after elution with 5 cm3 of HCl (1 mol dm−3), determined by ETAAS. At pH higher than 5.0, prewashing with 0.025 mol dm−3 HCl was applied prior to elution with 1 mol dm−3 HCl, to remove Al(OH)3 adsorbed on the column resin. The distribution of aluminium species over a pH range from 3.0 to 8.0 in synthetic standard solutions was closely matched by the 8-hydroxyquinoline spectrophotometric method and reported calculated data. Good reproducibility of measurement (± 1.5%) was obtained (10 ng cm−3 of Al, pH 4.0). LOD (3[sgrave]) for separated aluminium species (50 cm3 of sample) was found to be 0.3 ng cm3. The influence of some inorganic and organic complexing ligands as well as the effect of high salinity, nonionic surfactants and an excess of alkaline-earth ions on aluminium speciation was investigated. The technique was successfully employed in determination of aluminium species in various water samples from the environment.