Application of L-leucine-based natural deep eutectic solvent and ferroferric oxide magnetic nanoparticles modified with silica and zeolitic imidazolate framework-8 (Fe3O4@SiO2@ZIF-8) for extracting organophosphorus pesticides from cucumber.

An amino acid-based natural deep eutectic solvent (AABNADES) consisting of L-leucine, thymol, and lactic acid developed as a media for removing interfering agents, along with a magnetic adsorbent called ferroferric oxide modified with silica and zeolitic imidazolate framework-8 (Fe3O4@SiO2@ZIF-8) to determine the residue of four organophosphorus (OPs) pesticides in cucumber samples. The AABNADES was characterized using fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Magnetic adsorbents were characterized via field emission scanning electron microscopy (FESEM) and FTIR. Extraction conditions were optimized using response surface methodology (RSM) with a Box-Behnken design (BBD). The method was linear, accurate, and in the range of 10-50 μg/l. The detection and quantification limits ranged from 2.88-5.95 and 8.73-18.05 μg/l, respectively. The recovery for pesticide residues ranged from 97.1-143.2 % with a relative standard deviation of 3.97-12.24 %. The method is cost-effective, suitable for analyzing OPs in cucumber, and minimizes the use of harmful solvents.