On-line preconcentration of aluminium, gallium and indium with quinolin-8-ol for determination by atomic absorption spectrometry

Abstract

A study of the chemistry of aluminium, gallium and indium ions in solution, their behaviour under different pH conditions and their complexation with different buffering reagents was used to develop on-line preconcentration procedures for the determination of the elements by flame atomic absorption spectrometry. The buffers investigated were acetate, ammonium chloride, citrate, maleate, malonate, oxalate, picolinate and tartrate. A column of quinolin-8-ol, immobilized or controlled-pore glass, was used to collect the elements from the buffered solutions. The best buffer for aluminium was 0.1 mol l^–1 malonate at pH 10. The optimum buffer for gallium and indium was also 0.1 mol l^–1 malonate at pH ranges of 8–10 and 9.2–10, respectively. The use of malonate buffer makes a common procedure possible for all three elements. The collected analyte was eluted from the column with a mixture of hydrochloric and nitric acids, each at a concentration of 1 mol l^–1. For a collection time of 3 min, at a flow rate of 6 ml min^–1, the detection limit for all three elements was approximately 3 ng ml^–1, with enrichment factors of between 70 and 80. Interference effects were studied and the procedures developed were applied to the analysis of natural waters.