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.