On-line preconcentration of aluminium with immobilized 8-hydroxyquinoline for determination by atomic absorption spectrometry

Knowledge of the chemistry of Al in solution, its behaviour under different pH conditions and its complexation with different buffering reagents has been used to devise and optimize an on-line preconcentration procedure for the determination of Al by flame atomic absorption spectrometry. A column of 8-hydroxyquinoline immobilized on controlled-pore glass is used to collect Al in a buffer of 0.1 mol dm–3 malonate at pH 10. The Al is eluted into the nebulizer of a dinitrogen oxide–acetylene flame with a mixture of 1 mol dm–3 HCl and 1 mol dm–3 HNO3. For a collection period of 3 min at a flow rate of 6 cm3 min–1, the detection limit is 3 ng cm–3 with an enrichment factor of 76. The method has been applied successfully to river and sea-waters.