SYSTEMATIC INVESTIGATION OF ALUMINUM INTERFERENCES ON THE ALKALINE-EARTH ELEMENTS IN FLAME ATOMIC-ABSORPTION SPECTROMETRY .3. THE BEHAVIOR OF STRONTIUM AND BARIUM

Test solutions of Sr-Al and Ba-Al (+ Cs as ionization buffer), all for med from their chloridic salts in a H2O matrix, together with the rele asing agent La or chelating agents [ethylenediaminetetraacetic acid (E DTA) 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 oxi de-acetylene flame the addition of 1-5% La or 0.1 mol 1-1 EDTA is very effective for the determination of Sr, since its sensitivity is incre ased in this flame. The protecting agent quinolin-8-ol (2%) yielded th e best results, suppressing at least 1000 mg l-1 of Al. Barium also sh ows a very good sensitivity in this medium, thereby enabling a high di lution which removes Al interferences of at least 1 000 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 effi cient for the determination of Sr or Ba.