DES-based eutectogel as a smart sorbent for selective microextraction of phthalates in physiological saline prior to GC-MS analysis.

In this study, a novel deep eutectic solvent (DES)-based eutectogel was developed as a functional and smart sorbent for the selective extraction and determination of phthalates in aqueous matrices using gas chromatography-mass spectrometry (GC-MS). Unlike conventional approaches, where DESs serve mainly as environmentally friendly extraction media, the proposed system exploits their role as active components incorporated into a polymeric matrix, enabling enhanced analyte-sorbent interactions and improved extraction selectivity. The developed method exhibited satisfactory analytical performance, including good linearity in the concentration range of 0.25-20.0 μg mL-1 (R2 = 0.9937-0.9987), low limits of detection (0.066-0.18 μg mL-1) and quantification (0.20-0.53 μg mL-1), as well as acceptable analytical performance. Adsorption studies revealed that the extraction process follows the Langmuir isotherm model, indicating monolayer adsorption on a relatively homogeneous surface. Importantly, the eutectogel demonstrated pronounced selectivity toward phthalates, which increased with alkyl chain length. This behavior was attributed to enhanced hydrophobic interactions, stronger van der Waals forces, and preferential partitioning of nonpolar analytes into the DES-rich phase. These findings confirm the active role of the DES in governing analyte recognition and retention, highlighting the potential of DES-based materials as smart sorbents in analytical chemistry. The sorbent also exhibited good reusability, maintaining stable extraction efficiency over multiple cycles. Application to real samples revealed the presence of di (2-ethylhexyl) phthalate (DEHP) in all analyzed physiological saline solutions, indicating possible migration from packaging materials and a potential route of human exposure.