A novel composite based on cellulose and hyper-crosslinked polystyrene for spin column microextraction of fluoroquinolones from human serum prior to their LC-MS/MS determination.

A composite based on cellulose and hyper-crosslinked polystyrene (cellulose-HCP) was developed as a novel sorbent for micro-solid-phase extraction (μSPE) using spin columns. The composite was prepared via a simple, low-cost, and environmentally friendly procedure based on cellulose dissolution in NaOH solution. The extraction conditions were systematically optimized with respect to sorbent amount, centrifugation parameters, solution pH, and desorption conditions. Quantitative extraction of fluoroquinolones (98%, RSD ≤ 2%) were achieved at pH 5.8 using spin columns packed with three composite disks and centrifugation at 1500 rpm for 1 min. Efficient desorption was obtained using an acetonitrile-ammonia mixture (1:1, v/v). The method was validated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of fluoroquinolones in human serum. Good linearity was observed in the range of 2.0-400 μg L-1 (R2 ≥ 0.9916) with limits of detection of 0.3-0.7 μg L-1. Matrix effects were negligible (ME ≤ ±16%), and satisfactory reproducibility was achieved (RSD < 18%). The total sample preparation took 24 min and required only a centrifuge without protein precipitation. The proposed approach combines simplicity, rapidity, and low solvent consumption, meeting the principles of green sample preparation and demonstrating its suitability for the determination of fluoroquinolones in human serum.