Element determination in volatile oil containing fennel (Foeniculum vulgare) by ICP-OES and polarography

Fennel (Foeniculum vulgare) is frequently used for making tea and it is also applied as spice. Since the digestion of oils is relatively difficult and the undigested oil may greatly alter the element data, three different acid mixtures (nitric acid and hydrogen peroxide; nitric acid, hydrochloric acid and hydrogen peroxide; nitric acid, hydrochloric acid and hydrofluoric acid) were tested for determination of element content in fennel. Inductively coupled plasma optical emission spectrometry (ICP-OES) and polarography were applied for the determination of elements (Al, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Ni, P, S, Se and Zn). The extraction was realised by using microwave digestion technique under low and high pressure. Lucerna p-alfalfa as reference material was used for the accuracy and precision of the analytical procedures. According to the results, it can be stated that the digestion of medicinal plants containing oil could be realised by aqua regia