Mineral content in legumes and nuts: contribution to the Spanish dietary intake

We evaluated the levels of essential elements as Cu, Cr, Fe and Zn, and toxic elements as Al, Ni, Pb and Cd in a total of 40 samples of different legumes and 56 samples of different nuts, that are widely consumed in Spain. These elements were determined in the samples mineralized with HNO3 and V2O5, using electrothermal atomic absorption spectrometry (ETAAS) as the analytical technique. Reliability of the procedure was checked by analysis of a certified reference material. No matrix effects were observed and aqueous standard solutions were used for calibration. In legumes, the levels ranged from 1.5–5.0 μg Cu/g, 0.05–0.60 μg Cr/g, 18.8–82.4 μg Fe/g, 32.6–70.2 μg Zn/g, 2.7–45.8 μg Al/g, 0.02–0.35 μg Ni/g, 0.32–0.70 μg Pb/g and not detectable—0.018 μg Cd/g. In nuts, the levels ranged from 4.0–25.6 μg Cu/g, 0.25–1.05 μg Cr/g, 7.3–75.6 μg Fe/g, 25.6–69.0 μg Zn/g, 1.2–20.1 μg Al/g, 0.10–0.64 μg Ni/g, 0.14–0.39 μg Pb/g, and not detectable—0.018 μg Cd/g. A direct statistical correlation between Cu–Cr, Zn–Al and Cr–Ni (P<0.05), and Al–Pb (P<0.001), has been found. The growing popularity of these products in recent years on the basis of its nutritional properties and beneficial effects, requires additional data and a periodical control. In addition, the present findings are of potential use to food composition tables.