Metal Content of Nutritional and Toxic Value in Different Types of Brazilian Propolis

Abstract

Brazilian raw propolis samples (brown, green, red, and yellow) were investigated to evaluate the content of three elements of nutritional value (Cu, K, and Se) and three toxic metals (As, Cd, and Pb). The propolis samples (<i>n</i> = 19) were obtained from different regions of Brazil and analysed by atomic absorption spectrometry after microwave-assisted digestion. A descriptive analysis of the variables was carried out, and nonparametric tests (Kruskal-Wallis or Mann-Whitney) were performed to verify the differences in metal contents. The elemental concentrations of the Brazilian propolis were in the following ranges: As < 0.048-8.47 <i>μ</i>g·g^-1, Pb < 0.006-0.72 <i>μ</i>g·g^-1, Cu 0.57-11.60 <i>μ</i>g·g^-1, Se < 0.041-0.54 <i>μ</i>g·g^-1, and K 0.23-7.94 mg·g^-1; Cd was below LOD (0.008 <i>μ</i>g·g^-1) in all samples, except one. Seven samples exceeded the limits defined for As or Pb by the Brazilian regulation.