Establishment of an inorganic elements measuring method for determining the geographic origin of Welsh onion and preliminary examination

A method to quantify 22 inorganic elements in order to determination of the geographic origin of Welsh onion (Allium fistulosum L.) was established. A sodium extraction method with 1% HCl and an acid digestion method with HNO3/HClO4 and HNO3/HClO4/HF were studied and compared by using certified reference materials of Spinach Leaves and Apple Leaves. As a result, we applied a Na extraction method with 1% HCl and a HNO3/HClO4/HF digestion method to an inorganic elements measurement of Welsh onion. After analyzing different parts (lower, middle and upper, as well as outer and center) of Welsh onion, we decided to analyze a 10 cm part located in the lower part of Welsh onion and 22 elements. We determined Na by flame atomic absorption spectroscopy; Mg, P, K, Ca, Mn, Fe, Cu, Zn, Sr and Ba by ICP-AES; and Al, Co, Ni, Rb, Mo, Cd, Cs, La, Ce, Tl and Pb by ICP-MS in sample solutions. A principal component analysis using 22 elements for 47 Japanese and 15 Chinese samples showed a different tendency, and suggested that Chinese Welsh onions could be distinguished from Japanese ones.