Determination of bismuth, selenium and tellurium in nickel-based alloys and pure copper by flow-injection hydride generation atomic absorption spectrometry—with ascorbic acid prereduction and cupferron chelation-extraction

Diverse matrix effects on the determination of bismuth, selenium and tellurium (μg g⁻¹) in nickel-based alloys and pure copper by flow-injection hydride generation atomic absorption spectrometry (FIAS-HGAAS) were investigated. Sodium tetrahydroborate was used as the reductant. The separation of analytes from copper matrix was mandatory while the analytes were successfully determined without being separated from the alloy matrix. Hydrochloric acid was effective in the prereduction of bismuth and selenium, however, it did not give any satisfactory result for tellurium in nickel-based alloys. In this work, 5% (w/v) ascorbic acid was proved effective for the prereduction of tellurium.Successful determination of tellurium in copper was achieved when N-nitroso-N-phenylhydroxylamine (cupferron) chelation-extraction was employed for the separation of tellurium from copper matrix. Cupferron chelation-extraction was performed in phosphate buffer (a mixture of 0.2 mol l⁻¹ sodium phosphate and 0.1 mol l⁻¹ citric acid). Lanthanum hydroxide coprecipitation at pH 10.0±0.5 was effective for bismuth and selenium. Standard reference materials of nickel-based alloys and pure copper were analyzed using the proposed methods. The linear range for the calibration curves were 0.30-15 and 0.20-10 ng ml⁻¹ for BiH₃ and H₂Se, respectively, with a correlation coefficient of 0.9995. For H₂Te, the linear range for the calibration curves was 0.50-12 ng ml⁻¹ with the correlation coefficient of 0.9994. Good agreement was obtained between experimental values and certified values. Satisfactory recovery ranged from 91±1 to 106±2% was obtained from five replicate determinations.