Abstract

The seeds of Nigella sativa are used commonly in the Middle East as a traditional medicine to treat a variety of health conditions. Its seeds and oil have been used for centuries in the Islamic World, as sacred and holistic medicine. It has been also used in India and other countries for similar purposes. In the Middle East, it is a popular addition to the traditional diet, and is often mixed with either bread or honey. Commercial use of these seeds has recently been extended to many products including shampoos, oils, soaps, etc. The plant is also commonly known as black seeds, black cumin and black caraway seed. Twenty five seed samples of Nigella sativa were collected from four Middle Eastern countries: Qatar, Palestine, Egypt and Syria. Two analytical methods (XRF and ICP/OES) were used for the determination of Ag, Al, As, Ba, Br, Ca, Cl, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Ni, P, Pb, Rb, S, Se, Si, Sr, Th, Ti, Zn and U. Concentrations of Ca and K were found in all samples at the percentage levels. Ag, As, Co, Pb, Se, Si, Th and U were below the lower limit of detection of both analytical methods. The remaining elements were found in considerable concentrations in all the samples from the four countries. Nigella seeds provide relatively high amounts of some essential nutrients including Mn, Zn, Cu and Fe. Although the therapeutic mechanism of Nigella sativa is unknown, the presence of the trace elements that are essential nutrients and important for immune functioning, such as Mn, Fe, Cu, and Zn, suggests one possible mechanism.

Key words: Nigella sativa, trace metals, ICP/OES, EMMA/XRF.