Novel photo-responsive deep eutectic solvents: preparation, characterization and application in the detection of chlorpyrifos residues in apples and grapes

Abstract

Chlorpyrifos, an organophosphorus pesticide, poses health risks when present as a residue in fruits. This study reports the development of a novel photo-responsive deep eutectic solvent (PR-DES) for the sensitive and accurate detection of trace chlorpyrifos residues in fruit samples. The successful synthesis of the PR-DES was confirmed by FT-IR, ¹H NMR, UV-vis, and thermogravimetric analyses. By coupling the PR-DES with UV-vis detection, a green, cost-effective analytical method was developed for chlorpyrifos measurements, achieving a low limit of detection (16.19 µg L⁻¹) and quantification (53.99 µg L⁻¹). For spiked fruit samples, this method exhibited high average recoveries (98.6–102.4%) and low relative standard deviations (0.63–2.50%). Notably, chlorpyrifos can be hydrolyzed and removed post-analysis, whereas the photo-responsive component of the PR-DES was recyclable, promoting sustainable chemical practices. This design strategy of the PR-DES enriches the structural diversity and functional responsiveness of the DES, thereby broadening its potential applications in analytical and environmental chemistry.