Determination of aluminium using high performance chelation ion chromatography

The suitability of high performance chelation ion chromatography (HPCIC) using postcolumn reaction for the separation and determination of dissolved aluminium in complex samples was investigated. Use of a chelating ion-exchanger allowed for differentiation between kinetically labile and kinetically stable species of aluminium. Separation through a combination of chelation and cation-exchange was achieved using a 200 x 4.0 mm id column packed with particles of silica functionalised with iminodiacetic acid, with nitric acid-potassium chloride eluents. A temperature anomaly causing a five-fold increase in column efficiency for aluminium is believed to be a result of localised temperature effects in the particular type of instrument used. Postcolumn reagents investigated for the photometric detection included Tiron, Pyrocatechol Violet, Chrome Azurol S, and Eriochrome Cyanine R. The lowest detection limit (2.7 microg/L for a 100 microL sample volume) was achieved using 0.25 mM Eriochrome Cyanine R in 0.2 M hexamine (pH 6.1) with 1 mM cetyltrimethylpyridium bromide (CTAB). The optimised HPCIC system was applied successfully to the quantification of labile aluminium in paper mill process water.