Sequential Injection-HG-AFS Determination of Arsenic and Mercury in Ores

Sequential injection (SI)-HG-AFS was applied to the determination of As and Hg in ores. Sample of ores was digested with HCl and HNO3 and the solution obtained was treated with hydroxylamine hydrochloride to eliminate the action of oxidizing reagents introduced during sample digestion. Hydride of As and vapour of Hg were generated from HCl (2+98) solution using solution of 10 g·L-1 (for As) and 5 g·L-1 (for Hg) KBH4 solution as reducing reagent. Linear relationships between the magnitude of fluorescence intensity and mass concentration of As and Hg were found in the ranges within 100 and 10 μg·L-1, with detection limits (3s) of 0.05 and 0.02 μg·L-1 respectively. The proposed method was applied to the determination of As and Hg in samples of copper concentrate ores, manganese ores and iron ores, giving results in consistency with the certified or known values, and values of RSD′s (n=10) obtained were in the range of 0.93%-8.1%.