Simultaneous Determination of Se and Te in Copper Concentrate by HG-AFS

The sample (0.500 0-1.000 0 g) was mixed thoroughly with 0.15 g of activated carbon and 3 g of a mixture of MgO, ZnO and Na₂CO₃ (mass ratio of 1 to 2 to 3) as collector. The mixture was roasted for 1 h at 750℃, to have the selenium and tellurium in the sample transformed to their sodium salt respectively. Water (50 mL) together with few drops of ethyl alcohol was added to the roasted residue, and the solution was then concentrated to 25 mL and finally diluted to 50 mL. An aliquot of 10.00 mL was diluted to 25 mL after addition of 7 mL of 3.6 mol·L^-1 HCl solution and 1 mL of 20 g·L^-1 FeCl₃ solution (as masking agent for interfering elements), and keeping it in a boiling water bath for 40 min. Se and Te in the solution were then determined by HG-AFS. Linear relationships between values of fluorescence intensity and mass concentration of Se and Te were found in the same range within 100 μg·L^-1, with detection limits (3s) of 0.037, 0.025 mg·kg^-1 respectively. The proposed method was used to determine Se and Te in 2 CRM's of GBW 07166 and GBW 07234, giving results in conformity with the certified values.