Bio-inspired ionic liquid design: An advanced and environmentally friendly microextraction method for the selective...

Accurate determination of gallic acid (GA), a potent antioxidant present in grapevine leaves, is essential for optimizing extraction processes in pharmaceutical and food applications. Therefore, developing highly selective and sensitive methods for its analysis in complex plant-derived matrices is critical. To address this, a bio-inspired ionic liquid based on the gallic acid structure was designed, specifically the ionic liquid 1-[(3,4,5-trihydroxybenzyl)methyl]pyridinium chloride ([GaPy][Cl]). This tailored ionic liquid enables precise and selective microextraction of gallic acid via a simple and well-defined mechanism, thus enhancing the accuracy of its quantification in complex plant-derived grapevine leaf matrices. The ionic liquid was successfully synthesized and characterized by various techniques, including NMR, FTIR, and elemental analysis. The extraction mechanism of gallic acid from grapevine leaf samples was elucidated through Density Functional Theory (DFT) calculations, which revealed that strong hydrogen bonding at multiple sites is responsible for the highly efficient interactions during the extraction process. Based on systematic experimental evaluations conducted using the developed microextraction method, the proposed approach successfully quantified gallic acid at very low concentrations, achieving a limit of detection (LOD) of 0.13 ng mL^-1. The method exhibits excellent precision, with intra-day and inter-day relative standard deviations (RSDs, n = 7) of 1.79 % and 2.74 %, respectively. Furthermore, recovery studies performed on various real samples-including grape leaves, grapes, grapevine stems, and selected aqueous matrices-yielded recoveries ranging from 94.6 % to 99.4 %, confirming the high accuracy and robust analytical performance of the method for the determination of gallic acid in complex matrices.