Recent Progress in Green Sample Preparation for Improved Plant-Based Natural Product and Phenolic Compound Analysis

Phenolic compounds, secondary metabolites, are essential products of plant metabolism. They are characterized by one or more aromatic rings attached to hydroxyl groups and are categorized into phenolic acids, flavonoids, tannins, stilbenes, and lignans. These compounds play critical roles in plants, contributing to pigmentation, astringency, UV protection, and defense against pests and pathogens. Widely distributed in fruits, vegetables, and other matrices, they are also extracted from waste and byproducts of the food production chain, aligning with sustainable practices. Research on phenolic compounds is extensive, driven by their significant health benefits and diverse biological activity. Extraction is the initial and critical step in their study, with efficiency influenced by factors such as the extraction method, plant matrix properties, solvent choice, temperature, pressure, and time. Recent years have seen a surge in studies on both conventional and innovative extraction methodologies, with a growing emphasis on green technologies. This review provides a comprehensive overview of advancements in green sample preparation (GSP) techniques within the framework of green analytical chemistry (GAC). It highlights strategies to minimize environmental impact, including the use of micro-techniques, assisted extraction methods, and eco-friendly solvents from renewable and non-toxic sources. Experimental design methods for optimizing phenolic compound yields are also discussed. Additionally, the review presents tools for assessing the greenness of sample preparation techniques, focusing on their environmental and operational improvements.