Natural deep eutectic solvents and natural solid biosorbents in microextraction techniques of organic compounds based on chromatographic techniques: A critical review

Analytical chemistry has increasingly focused on the environmental impact of its methods, with significant attention given to green principles in sample preparation. Techniques like Solid-Phase Microextraction (SPME), Micro-Solid-Phase Extraction (µ-SPE), Thin-Film Microextraction (TFME), Stir Bar Extraction (SBSE), Bar-Adsorptive Microextraction (BAµE), Disposable Pipette Extraction (DPX), and Rotative Disk Sorptive Extraction (RDSE) represent advancements in solid-phase extraction methods. Meanwhile, methods such as Single Drop Microextraction (SDME), Dispersive Liquid-Liquid Microextraction (DLLME), and Hollow Fiber Liquid-Phase Microextraction (HF-LPME) focus on liquid-phase techniques. Among the green approaches, biosorbents have gained prominence as extractor materials due to their environmental friendliness, renewability, biodegradability, and cost-effectiveness. In liquid-phase extractions, Natural Deep Eutectic Solvents (NADESs) have emerged as promising alternatives to traditional solvents. NADESs offer benefits such as biodegradability, biocompatibility, low toxicity, and affordability, along with ease of synthesis and purification. This review summarizes the application of NADESs and biopolymers, focusing in biosorbents, in microextraction and other techniques, based on literature from 2017 to the present. It is evident that NADESs present viable alternatives to conventional solvents, with their physical-chemical properties like viscosity, density, and polarity, being tunable through various mixtures. Similarly, biosorbents offer unique physicochemical properties that can outperform traditional commercial materials in sample preparation. Applications discussed in this review focus on the determination of organic compounds in environmental, food, and biological samples, utilizing chromatographic methods. These developments highlight the ongoing evolution in green analytical practices, aiming for more sustainable and efficient analytical procedures.