Using stripping voltammetry to determine heavy metals in cooking spices used in Iraq

Abstract

Monitoring heavy metals in herbs and spices is increasingly being reported from different parts of the world. In Iraq and the Middle East, there is limited information on the levels of heavy metals in these additives, although several spices are widely used in daily diets. In the present study the concentrations of Cu, Zn, Fe, Mn, Cr, Ni, Co, Cd, Pb, and Hg in 32 kinds of natural spices traditionally consumed in Iraq were determined by stripping voltammetry. The highest concentration found (in mg kg-1 dry weight) was that of iron (32.44-1,147) followed by manganese (6.42–285.8), zinc (5.45-129.3), and copper (2.58-30.71). The essential elements of chromium, nickel, and cobalt were found at comparatively lower concentrations of less than 5.900 mg kg-1, whereas the levels of the toxic elements Cd, Pb, and Hg were even lower (0.010-4.159 mg kg-1). Strong elemental correlations ( Ź0.500) exist between the transition metals Cu, Zn, Fe, Ni, Co, and Cr, reflecting their chemical nature and physiological functions. The average daily contribution of Cu, Fe, Mn, and Cr from spices to the Iraqi requirements was estimated to be 21-61% of the internationally recommended standards, while the levels of the toxic elements Cd, Pb, and Hg were low and were found to pose no threat to consumers.