Two novel strategies in food sample preparation for the analysis of dietary polyphenols: Micro-extraction techniques and new silica-based sorbent materials

Background: The multiple health promoting effects associated with the consumption of dietary polyphenols have increased research interest in recent years to develop advanced and environmentally friendly analytical approaches for correctly identify and quantify these compounds in different foodstuffs. However, food samples are highly complex matrices, what hinders determination of these compounds, which additionally, are usually found in food at low concentration levels, therefore a preliminary sample preparation method which provides adequate isolation and enrichment of analytes, as well as effective clean-up from matrices interferences, is often required prior to further analysis. Scope and approach: Current trends in sample preparation involves moving towards cheaper, cost-effective and more environmentally friendly procedures, by minimizing the number of steps and reducing the consumption of sample and organic solvents, replacing toxic solvents by non-toxic ones, and improving extraction efficiency and selectivity with the application of new advanced sorbents materials and micro-extraction techniques that overcome limitations of conventional sample preparation methods. Key findings and conclusions: This review provides an overview of the most relevant achievements and improvements in sample preparation and extraction methodologies applied for the determination of dietary polyphenols in food products, regarding the preparation of novel silica-based sorbent materials and the development of new micro-extraction methodologies, giving some recent examples from the last five years. The review gives an updated overview that emphasizes the new developments achieved, providing a broad view of the current trends and the future perspectives in the analysis of dietary polyphenols and expanding knowledge related to food quality.