Green multi-element analysis of unconventional food plants using a deep eutectic solvent-based extraction method

This study reports the first application of a deep eutectic solvent (DES) for multi-element extraction from eight unconventional food plants (UFPs): almeirão, assa-peixe, caruru, dente-de-leão, ora-pro-nobis, serralha, taioba, and trapoeraba. These species are recognized for their nutritional value and potential to enhance food security, yet their elemental composition remains poorly documented. A DES composed of choline chloride, malic acid, and water was synthesized and characterized by FTIR spectroscopy. Extraction conditions were optimized using a central composite design, with the best performance obtained at 1.8409 g DES, 60 °C, and 30 min. Elemental determination was performed by FAAS and ICP OES. Method validation with certified reference materials (NIST 1515 apple leaves, NIST 1547 peach leaves, and NIST 1570a spinach leaves) showed no significant matrix effects, high linearity (R 2 > 0.988), high precision (RSD ≤ 13%), and acceptable accuracy (recoveries 76–95% for Cu, K, Mg, Mn, and Zn), with low detection and quantification limits. Compared with acid digestion, the DES-based method provided similar recoveries for most elements while reducing reagent toxicity, waste generation, and energy consumption. AGREEprep assessment confirmed its greener profile, aligning with Green Analytical Chemistry principles and supporting Sustainable Development Goals (SDGs) 2 (Zero Hunger), 9 (Industry, Innovation and Infrastructure), 12 (Responsible Consumption and Production), and 15 (Life on Land). This approach enables reliable nutritional assessment of UFPs and supports their strategic inclusion in sustainable food systems.