Application of levulinic acid-based natural deep eutectic solvents for extraction and determination of deltamethrin in food samples

In the study, a fast and green natural deep eutectic solvent based ultrasound-assisted liquid liquid microextraction (NDES-UALLME) were proposed for the determination and extraction of deltamethrin in food samples using UV/Vis spectrophotometry. The extraction step was based on ion-pair formation between deltamethrin and levulinic acid-tetraethylammonium bromide (as extraction solvent) at pH 5.5, and then extraction of deltamethrin into micro-drops of extraction solvent by using tetrahydrofuran. Levulinic acid-based natural deep eutectic solvents composed of natural, green compounds, i.e., choline acetyl chloride, tetrabutylammonium bromide, tetraethylammonium chloride and tetraethylammonium bromide were used for the first time as extraction solvents for extraction of deltamethrin. The NDES-UALLME procedure allowed to exclude matrixes effects and increase enrichment factor (283) of deltamethrin. Several key factors, including the type and the volume of extraction solvent, the pH of sample solution, ultrasound time, extraction temperature, ionic strength and sample volume were optimized in detail. At optimized conditions, the NDES-UALLME procedure was characterized by low limit of detection (2.4 ng mL−1), a wide linear dynamic range (8–950 ng mL−1), quantitative recoveries (93 ± 4%-103 ± 2%) and acceptable relative standard deviations (2.9%≤). The validation of NDES-UALLME procedure was carried out using recovery tests, intraday and intraday studies. The applicability of NDES-UALLME procedure was confirmed by the assay of deltamethrin in real food samples.