A novel approach for the identification of cadmium-chelating compounds in plant-based foods using SEC-ICP-MS/MS and SEC-QTOF-MS.

The increasing trend towards more plant-based diets has underscored the need for a comprehensive understanding of the presence of potentially toxic elements in plant-based foods. Among these, cadmium is of particular concern due to its potential health risks. Our understanding of how cadmium is bound in plant-based foods and how this affects its bioavailability is currently limited. This paper introduces a qualitative methodology that combines SEC-ICP-MS/MS and SEC-QTOF-MS for identifying cadmium-chelating compounds and performing simultaneous speciation analysis of phosphorus, sulfur, calcium, iron, and zinc in plant-based foods. The present study details the optimization of the cadmium extraction process across seven different matrices with varying protein content. A large variation in the recoveries, ranging from 2.3 to 72.3%, was observed, suggesting strong cadmium binding to certain foods. The study employed two size exclusion columns (optimal ranges 0.1-7 kDa and 10-600 kDa), which were optimized for chromatographic peak resolution and analysis time to separate the extracted compounds. The study identified distinct cadmium-chelating patterns in plant-based foods, especially within the 1-20 kDa range. The multielement speciation data were used to detect proteins and other compounds, including phytic acid, phytochelatins, and metabolites, highlighting their chelating properties. The methodology established in this paper represents a significant step forward in cadmium speciation in plant-based foods and holds promise for future bioaccessibility studies.