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

Abstract

The flow injection hydride generation technique together with atomic absorption spectrometry was used for the determination of arsenic, antimony and selenium in the iron-based water treatment chemical FeClSO 4. Thiourea, l-cysteine and potassium iodide–ascorbic acid were used as masking agents to diminish the interference caused by the very high iron concentrations in the samples. These reagents act also as prereductants for As(V) and Sb(V). Thiourea and l-cysteine did not prevent the signal depression caused by such high iron content, but potassium iodide–ascorbic acid eliminated iron interference well even up to 2500 mg Fe l −1. The limits of detection (LODS) in aqueous solutions containing no iron were 0.037 μg l −1, 0.121 g l −1 and 0.131 μg l −1 for As, Sb and Se, respectively. The linear dynamic range was 0–10 μg l −1 for As and 0–30 μg l −1 for Sb and Se. The precision relative 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 FeClSO 4 matrix at the level 0.5–0.8 μg l −1 for the elements to be analyzed. The accuracies of the methods were tested by using two standard reference materials (SRM 361, LA Steel and SRM 2074, river sediment). The concentrations obtained for As, Sb and Se were very close to the certified values.