Vortex-assisted dispersive liquid–liquid microextraction based on the hydrophobic deep eutectic solvent–based ferrofluid for extraction and detection of myclobutanil

A vortex-assisted dispersive liquid–liquid microextraction (VA-DLLME) procedure using hydrophobic deep eutectic solvent–based ferrofluid (HDES-FF) as an extractant was established. The developed sample preparation method coupled with high-performance liquid chromatography–diode array detector (HPLC–DAD) was applied to the pretreatment and determination of myclobutanil (MYC) in fruit juice. Hydrophobic deep eutectic solvent, synthesized by n-decanoic acid and dl -menthol, was as a carrier and combined with magnetic nanoparticles (Fe 3 O 4 @OA) to form HDES-FF as an extractant with high extraction capacity. The synthesized materials were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Parameters affecting extraction efficiency were optimized using single-factor experiments and Box-Behnken design via response surface methodology (BBD-RSM). Parallel tests were performed three times under the optimal conditions predicted by the model, yielding an actual mean recovery of 94.77% with RSD of 2.7% ( n = 3) and an enrichment factor of 41.8 ± 0.98 (mean value ± SD, n = 3). Under the optimal conditions, the linear range was 1.0–100.0 µg·mL −1 ; the limit of detection (LOD) and limit of quantification (LOQ) were 0.25 and 0.80 µg·mL −1 , respectively. The average spiked recoveries in the samples ranged from 98.2 to 100.5% with intra-day relative standard deviations (RSDs) of 1.2–3.5% ( n = 3) and inter-day RSDs of 1.1–3.8% ( n = 3). Finally, the method was successfully applied to the determination of MYC antimicrobial agent in different fruit juice samples. The proposed HDES-FF-VA-DLLME/HPLC–DAD method was verified to widely apply to the extraction of triazole fungicides. Graphical Abstract