Systematic investigation of aluminium interferences on the alkaline earth elements in flame atomic absorption spectrometry. Part III. The behaviour of strontium and barium

Abstract

Test solutions of Sr–Al and Ba–Al (+Cs as ionization buffer), all formed from their chloridic salts in a H₂O matrix, together with the releasing agent La or chelating agents [ethylenediaminetetraacetic acid (EDTA) and quinolin-8-ol] as protecting agents were investigated in both nitrous oxide–acetylene and air-acetylene flames in order to quantify the extent of removal of Al induced interferences. In the nitrous oxide–acetylene flame the addition of 1–5% La or 0.1 mol l^–1 EDTA is very effective for the determination of Sr, since its sensitivity is increased in this flame. The protecting agent quinolin-8-ol (2%) yielded the best results, suppressing at least 1000 mg l^–1 of Al. Barium also shows a very good sensitivity in this medium, thereby enabling a high dilution which removes Al interferences of at least 1000 mg l^–1 in the presence of 1% La or 2% quinolin-8-ol. The cooler air–acetylene flame in the presence of La or chelating agents in the solutions is not efficient for the determination of Sr or Ba.