Determination of 12 Kinds of Fluoroquinolones in Water and Milk Samples by Magnetic Fluorinated Graphene Solid-phase Extraction-Liquid Chromatography-High Resolution Mass Spectrometry

The magnetic fluorinated graphene (Fe3O4/FG) was prepared by one-step solvothermal method and applied as adsorbent material for enrichment and purification of 12 kinds of fluoroquinolone drugs (FQs) in water and milk samples, then the FQs were detected by high-performance liquid chromatography combined with quadrupole/orbitrap high-resolution mass spectrometry (HPLC-Q/Orbitrap HRMS). The morphology, crystal structure, magnetic strength, and specific surface area of Fe3O4/FG were systematically characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and specific surface area analyzer (BET). The single factor optimization method was used to optimize the magnetic solid-phase extraction (MSPE) parameters such as adsorbent dosage, extraction time, ion strength, sample pH, type and volume of elution. Under optimal conditions, due to the synergistic effect of the surface π-electrons system and fluorine (F) atoms on the surface of FG, Fe3O4/FG exhibited excellent adsorption performance by generating various forces such as π-π-conjugation, F-F interactions, and hydrogen bonding with FQs. The methodological validation results showed that the 12 kinds of FQs had good linear relationships, with correlation coefficient (R2) ≥ 0.999. The method limits of detection (MLOD) of 12 kinds of FQs in water and milk samples were 3–6 ng/L and 75–150 ng/L, respectively, and the method limits of quantification (MLOQ) were 10–20 ng/L and 250–500 ng/L, respectively. The established method was applied to determination of 12 kinds of FQs in water and milk samples, with spiked recoveries of 79.3%–108.4% and relative standard deviations (RSDs, n=3) of 1.5%–8.6% in water samples, and spiked recoveries of 75.6%–105.4% and RSDs (n=3) of 2.3%–9.5% in milk samples.