Microwave Digestion Followed by ICP-OES for the Determination of Al, Cd, Cr, Cu, Fe, Ni, Pb, and Sn in Maize

Maize (Zea mays L.) is currently the most widely grown crop in the world and is used not only for food and animal feed but also to produce industrial starches, biodiesel, ethanol, and oils. The present work reports the results obtained by the proposed method for the determination of metals (M, Cd, Cr, Cu, Fe, Ni, Pb and Sn) in maize by ICP-OES, using digestion with an oxidant mixture in a closed-vessel microwave oven. The results in the maize samples (minimum-maximum in mg/kg) were: Al 6.678-7.051, Sn 2.092-3.977, Cr 0.394-0.423, Cu 21.56-24.78, Fe 93.37-102.86, Ni 1.679-1.877 and Pb 0.375-0.392. The concentration of Cd was below the detection limit (< 0.03 mg/kg). The certified reference material, CRM NIST1573a Tomato Leaves, was used in order to verify the accuracy of the microwave digestion method. The results of this study were in good agreement with the certified values.