Major, minor and trace metal composition of some selected vegetables

This paper describes the major, minor and trace metal composition of eight vegetables produced in the central region (CR) of Saudi Arabia. These vegetables, usually classified as modified stems or as modified roots, include potato, onion, string onion, garlic, carrot, radish, red radish and turnip. The dried samples of the vegetables were subjected to multi-element analysis using inductively coupled plasma mass spectrometry (ICP-MS) following microwave acid digestion in closed PTFE tubes. In general, the vegetables contained higher amounts of potassium than that of sodium. The sum of the concentrations of Na, K, Ca, Fe, Mg and Mn was highest in garlic and lowest in peeled potato samples. The root vegetables (carrot, radish, red radish and turnip) were better sources of Ca and Na than the stem vegetables (potato, onion, and garlic) but the latter contained higher amounts of K, Fe, Mg and Mn. The average concentrations of Zn, Cu, Mo and V were higher in stem vegetables while Cr and Sr dominated in the root type vegetables. In terms of the toxic Pb, Cd and Ni contents, these vegetables were found to be much safer than those grown on the western region of Saudi Arabia and are well within the safety limits established by EEC standards. Further studies are highly essential in order to fully characterize the undesirable variations in the heavy metal content observed among vegetables grown in the two regions of Saudi Arabia.