Determination of Cr and Ni in Orujo spirit samples by ETAAS using different chemical modifiers

Several analytical methods are proposed for chromium and nickel determination in Orujo spirit samples using ETAAS. Permanent chemical modifiers such as W, Ir, Ru, W–Ir and W–Ru were comparatively studied in relation to the common chemical modifier employed, Pd(NO3)2–Mg(NO3)2. Taking into account the analytical performance, the method based on the use of Ru as a permanent modifier was selected for further direct Cr determinations in Orujo samples. In the case of Ni, after comparison among the different methods developed, a method with no modifier which allows the direct interpolation in calibration graphs was chosen. Detection limits of 0.13 μg L−1 and 0.30 μg L−1 were obtained for Cr and Ni, respectively. For all methods developed, recoveries (ranged 98.6–102%) and precision (RSD < 10%) were acceptable. The selected methods were applied for the determination of the Cr and Ni contents in 80 representative Orujo Galician samples. The Cr concentrations ranged from <LOD and 14.61 μg L−1 and Ni concentrations ranged <LOD and 34.17 μg L−1.