Determination of selenium in Italian rices by differential pulse cathodic stripping voltammetry

The total selenium content in white, black, red rice and white rice hull samples, grown in Northern Italy cultivars, has been determined using the differential pulse cathodic stripping voltammetry (DPCSV) on the hanging drop mercury electrode (HDME), in the presence of Cu(II). The digestion was performed in open vessel through a combination of wet acid/dry ashing with Mg(II) salts. The calibration curve was linear in the concentration range 0.15–8 ppb, the detection limit was estimated to be 0.07 ppb, and the recovery was in the range 85–102%. Reproducibility was from 1.9% to 9.0% (RSD, n = 4). Rice samples were analyzed by the standard addition method and the results were compared with those obtained by a spectroscopic technique (HG-ICP-AES). The proposed procedure, sensitive, inexpensive, easy-to-handle and precise can be successfully applied for the determination of selenium in nutritional products. The resulting selenium contents in different Italian rice varieties were: 20.1 ± 1.8 ppb (white), 53.0 ± 1.0 ppb (red), 26.7 ± 1.3 ppb (black), 45.3 ± 4.1 ppb (white rice hull).