Speciation analysis of copper and zinc in plant-based drinks using hyphenated techniques

Abstract

Over the past few years, the market for vegetarian and vegan products has been one of the fastest growing. There is an increasing trend of consumers limiting their meat intake and, therefore, a huge demand for vegan products. Substitutes for milk - plant-based drinks - are the most popular, followed by plant burgers, yoghurts, and cheese. For a better understanding of the bioavailability of elements and their effects on our bodies, it is crucial to know the nature of the occurrence of a specific element, not just its overall content.The application of combined experimental techniques, that is, the techniques of separation (HPLC) hyphenated with the element-specific (ICP-MS/MS) and molecular-specific detection technique (ESI-MS/MS), permits speciation analysis of metals present in trace amounts in the material studied (food products of plant origin) and identification of ligands involved in complexes. Identifying the groups of ligands binding metals in plants prompts further studies to determine the effect of the ligand on the metals' bioavailability and understand the factors that govern their absorption. In this study, they are used to identify the nature of ligands of copper and zinc complexes in widely used rice and millet-based drinks.The results obtained by the presented method permitted the identification of the ligands binding copper and zinc – amino acids, organic acids and the most studied plant metal chelator – nicotionamine.