Levels of essential and non-essential metals in linseed (Linum usitatissimum) cultivated in Ethiopia

Abstract

The levels of essential and non-essential metals were determined in linseed (Linum usitatissimum) samples collected in November 2011 from five different sites (Bale, East Gojam, Shoa, South Wello and Tigray) in Ethiopia where its cultivation is common. A 0.5 g dried powdered linseed was digested with 2 mL of nitric acid (HNO₃), 1 mL of perchloric acid (HClO₄) and 1 mL of hydrogen peroxide (H₂O₂) at 270 ^oC for 2:30 hours and the levels of metals determined by flame atomic absorption spectrometer. The accuracy of the optimized procedure was evaluated by analyzing the digest of the spiked samples with standard solution. Recoveries of the spiked samples varied from 91% to 109%. The levels (mg kg^-1) of metals determined were in the ranges Na (242–614), K (6,494–6,755), Mg (2,679–3,118), Ca (540–744), Cr (13–30), Mn (17–28), Fe (198–242), Co (23–42), Ni (12–16), Cu (25–45), Zn (29–40), and Pb (12–32). Cd was below method detection limit. K and Fe were with the highest concentration from major and trace metals, respectively. Analysis of variance (ANOVA) at 95% confidence level indicated that there is significant difference in the levels of all metals between the five samples means except K and Ni. The results indicated that Ethiopian linseed is a good source of essential metals and free from the toxic metal Cd but not from Pb.

KEY WORDS: Linseed, Linum usitatissimum, Essential metals, Non-essential metals, Ethiopia

Bull. Chem. Soc. Ethiop. 2014, 28(3), 349-362.

DOI: http://dx.doi.org/10.4314/bcse.v28i3.4