Distribuição de cromo e tálio em suplementos alimentares e águas estuarinas empregando voltametria associada à decomposição de amostras por radiação UV e de microondas

Abstract

A methodology was developed, optimized and validated for the determination of chromium and thallium in dietary supplements of different classes (protein and/or carbohydrate concentrates, multivitamins, meal replacements, stimulants and others) using the anodic stripping voltammetry (ASV) technique. This methodology was validated, following all the necessary validation parameters, and applied to 39 products that were sold in the Brazilian market between 2014–2017. The results obtained were compared with the results obtained in the technique of ICP-OES, in order to bring a confirmatory answer. Finally, an assessment of the risk to human health in the ingestion of these products was made. There are no regulations that stipulate a limit on the concentration of thallium in dietary supplements in current legislation around the world. To assess the non-carcinogenic risk, the Hazard quotient was used, calculated from the oral reference dose provisionally established by the US EPA in 2012. When comparing the concentrations of thallium ingested daily from the dose recommended by the consumer of each product with lethal doses for humans estimated in other studies, it is noted that although lower, the concentrations found are significant in several of the evaluated products, representing a potential health risk. This risk is intensified by the potential for bioaccumulation of thallium in the body, in addition to the fact that it is common for consumers to use more than one product simultaneously for a prolonged period of time. Although the Amazon River has the largest drainage basin in the world, recent trace metal data on this estuary and the associated mixing plume is still sparse. In this sense, this work provides a comprehensive distribution study for Cr and Tl species in the Amazon and Pará River estuaries and the surrounding regions of the Northwest Brazilian Continental Shelf. Chromium and Tl were determined sequentially by cathodic and anodic stripping voltammetry (CSV and ASV) in samples collected during the RV Meteor cruise M147 (2018). The analyses of total Cr and Tl species were conducted in the presence of diethylenetriamine pentaacetic acid (DTPA) as a complexing reagent after the sample digestion by UV irradiation. Beyond the determination of total dissolvable (including >0.2 µm particulates) and total dissolved (<0.2 µm) species, the size fractionation was also investigated in 0.015 μm filtered samples for the calculation of the colloidal fraction (0.015-0.2 µm). The results provided insight into the input and removal processes influencing the transport of Cr and Tl species along this highly dynamic region.