The genus Protium Burm f., the most abundant of the Burseraceae family, has its primary center of diversity in the Amazon. Its main characteristic is the exudation of "Breu", an aromatic resin collected directly from the trunk of the trees. Stimulating pastes have been used to increase resin flow, such as 2-chloroethylphosphonic (Ethephon).It is important to evaluate variations in the composition of the resin extracted naturally and with the use of the stimulant, to guarantee the product quality. The inorganic analysis is also fundamental to verify the presence of compounds harmful to health.A quali-quantitative elemental variation of the resin between the two extraction modes was proved by WD-XRF analysis. In 15 samples, Mg and F were only observed in those using Ethephon. In samples from the same tree, the qualitative difference is 54%, proving a discrepancy in the chemical composition of Breu, which can alter its properties.