Determination of Norfloxacin and Enrofloxacin in milk using deep eutectic solvent-based ferromagnetic fluid by UV-HPLC

An ultrasonic-assisted liquid-liquid microextraction pretreatment method was developed using magnetic nanoparticles and deep eutectic solvent, and employed to separate the Norfloxacin and Enrofloxacin from pure milk samples by ultraviolet-high performance liquid chromatography. A DES-based ferromagnetic fluid with strong extraction power was prepared through the ultrasonic treatment of deep eutectic solvent (HBA: HBD = 1:2) and magnetic nanoparticles. The exceptional repeatability, reproducibility and long-term stability effect was mainly achieved through the strong interactions between the extractant and the analyte, such as hydrophobic interaction, hydrogen bond attraction, and electrostatic interaction. The results showed that the Norfloxacin and Enrofloxacin presented good linear relationship within the concentration range of 0.005 ∼ 500 mg/mL, with detection limits of 0.00035 mg/mL. The method was successfully applied to determine Norfloxacin and Enrofloxacin in milk samples by HPLC with acceptable recovery of 81 ∼ 104% and relative standard deviations (RSD) below 3%. The established method was simple, rapid and efficient, making it applicable for the detection of Norfloxacin and Enrofloxacin residues in milk. The results of this study were compared with reported methods in the literature revealing its advantages.