The procedure for sample preparation, according to Figure 1, consisted of weighing 2.5 g of honey in a 50 mL polypropylene tube with cap, then heating this sample, in water bath at 45 °C, during 1 min for better homogenization. After this, 5.0 mL of aqueous 0.1 mol L-1 Na2EDTA, also heated at 45 °C, and 5.0 mL of acetonitrile were added.