The pervasive presence of pesticide residues in aquatic environments poses significant risks to both ecosystems and human health. In response to the growing need for environmentally sustainable analytical techniques, we present a novel in-syringe dispersive liquid–liquid microextraction (IS-DLLME) method utilizing a natural deep eutectic solvent (DES) for the extraction of selected pesticides from water samples.

In this study, the DES was synthesized from choline chloride and a hydrogen bond donor, offering a biodegradable and non-volatile alternative to traditional organic solvents. The microextraction was carried out inside a standard plastic syringe, eliminating the need for additional equipment and minimizing solvent consumption. Following extraction, analytes were separated and quantified using gas chromatography–mass spectrometry (GC-MS).

The method demonstrated excellent analytical performance, with extraction recoveries ranging from 86% to 97%, relative standard deviations below 4.5%, and limits of detection in the low µg/L range. The linearity was confirmed over a broad concentration range, and matrix effects were negligible. Application to environmental water samples confirmed the method's robustness and applicability to real-world analysis.

This work highlights the potential of combining IS-DLLME with DESs for rapid and sustainable monitoring of trace contaminants in water. The integration of green chemistry principles into sample preparation not only enhances analytical performance but also supports safer and more eco-conscious laboratory practices.