Evaluation of Polycyclic Aromatic Hydrocarbons in Dried Leaves of Yerba Mate (Ilex paraguariensis) and Their Extraction into Infusions

Herbal teas and yerba mate infusions are an important part of the human diet that may contain toxic contaminants due to the industrial processing of the herbal material. The presence of the lipophilic compounds polycyclic aromatic hydrocarbons (PAHs) was investigated in dry yerba mate samples and how they transfer into the infusions. Samples were selected among eight different brands, and three types of yerba mate products (aged, green, and roasted). Synchronized fluorescence scanning (SFS) was used as primary screening method for PAHs in dried yerba mate, and high-performance liquid chromatography with fluorescence detection for the analysis of the infusions. SFS screening showed presence of PAHs in the dry herbal material, and the PAHs ratios suggest that the contamination originates from pyrogenic sources. Using an experimental setup to simulate the traditional yerba mate consumption (successive extractions with small amounts of water), the sum of the six PAHs in each infusion of yerba mate sample ranged from 4.8 to 30.2 ng g−1. Benzo [a] pyrene concentration ranged from n.d. to 1.1 ng g−1 while phenanthrene reached a maximum of 59 ng g −1 in the yerba mate samples tested. An estimated 0.11% to 0.54% of the six PAH analytes were transferred into the infusion and the SFS method can be used to screen the presence of PAHs in the dry material. The chemical profile of the most abundant PAHs found in the infusions indicate a low total equivalent exposure index.