Graphene oxide composites for magnetic solid-phase extraction of twelve quinolones in water samples followed by MALDI-TOF MS

Antibiotic compounds in natural waters are normally present at low concentrations. In this paper, an easy and highly sensitive screening method using graphene oxide–functionalized magnetic composites (GO@NH 2 @Fe 3 O 4 ) combined with matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) was established for twelve quinolone antibiotics. GO@NH 2 @Fe 3 O 4 composites were utilized as adsorbents for magnetic solid-phase extraction. This method combines the advantages of magnetic solid-phase extraction and MALDI-TOF MS, which allows for fast detection of quinolones at low concentrations. To improve absorption efficiency, the following parameters were individually optimized: sample acidity, extraction time, amount of adsorbent used, eluent used, and desorption time. Under the optimum conditions, the established method gave a low detection limit of 0.010 mg/L and allowed the high-throughput screening of twelve quinolone antibiotics (enoxacin, norfloxacin, ciprofloxacin, pefloxacin, fleroxacin, gatifloxacin, enrofloxacin, levofloxacin, sparfloxacin, danofloxacin, difloxacin, and lomefloxacin). The proposed method, having an easily prepared sorbent with a high affinity for quinolones and a convenient, high-throughput detection step, has been shown to have merit for the detection of antibiotics in water samples. Graphical abstract Schematic illustration of the (A) preparation of GO@NH 2 @Fe 3 O 4 and (B) operating procedure for the MSPE and MALDI-TOF MS detection of QNs