Optimization of a flow injection hydride generation atomic absorption spectrometric method for the determination of arsenic, antimony and selenium iniron chloride/sulfate-based water treatment chemical

The flow injection hydride generation technique together with atomic absorp tion spectrometry was used for the determination of arsenic, antimony and s elenium in the iron-based water treatment chemical FeClSO4. Thiourea, L-cys teine and potassium iodide-ascorbic acid were used as masking agents to dim inish the interference caused by the very high iron concentrations in the s amples. These reagents act also as prereductants for As(V) and Sb(V). Thiou rea and L-cysteine did not prevent the signal depression caused by such hig h iron content, but potassium iodide-ascorbic acid eliminated iron interfer ence well even up to 2500 mg Fe 1(-1). The limits of detection (LODS) in aq ueous solutions containing no iron were 0.037 mug 1(-1) 0.121 g 1(-1) and 0 .131 mug 1(-1) for As, Sb and Se, respectively. The linear dynamic range wa s 0-10 mug 1(-1) for As and 0-30 mug 1(-1) for Sb and Se. The precision rel ative standard deviation was expressed as 2.6% for As, 4.4% for Sb and 2.9% for Se. The precision determinations were done on the FeClSO4 matrix at th e level 0.5-0.8 mug 1(-1) for the elements to be analyzed. The accuracies o f the methods were tested by using two standard reference materials (SRM 36 1, LA Steel and SRM 2074, river sediment). The concentrations obtained for As, Sb and Se were very close to the certified values. (C) 2001 Elsevier Sc ience B.V. All rights reserved.