Field isolation and capture of fluoroquinolones in the water environment with magnetic solid-phase extraction technique prior to HPLC quantification

A magnetic graphene oxide/chitosan composite (MGO@CS) was synthesized via mechanochemistry and applied as an adsorbent for magnetic solid-phase extraction of four fluoroquinolone antibiotics in environmental water, prior to HPLC-fluorescence detection. Characterization confirmed the composite structure, and MSPE parameters were optimized. Results showed chitosan incorporation significantly improved elution efficiency. The adsorbent demonstrated reusability for six cycles. Under optimal conditions, the method demonstrated excellent linearity (1.0 × 10−4–2.0 × 10−1 mg/L, R2 ≥ 0.9990), with detection limits of 6.4 × 10−5–5.7 × 10−3 mg/L and quantification limits of 2.7 × 10−4–3.2 × 10−2 mg/L. Analysis of spiked environmental water samples yielded recoveries of 82.1–100.4% with relative standard deviations (RSDs) of 1.2–8.6%. These findings indicate that the proposed method is both effective and economical for the analysis of fluoroquinolone antibiotics in environmental water samples.