PRECONCENTRATION OF QUINOLONES ON MAGNETIC HYPERCROSSLINKED POLYSTYRENE BEFORE THEIR DETERMINATION BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY IN MILK

Magnetic hypercrosslinked polystyrene (MHCPS) is proposed for group sorption isolation and preconcentration of quinolones. The conditions for magnetic solid-phase extraction are selected: 25 mL of solution (pH 6), sorbent mass 20 mg, sorption time 20 min. The analytes have been desorbed with 2 mL of methanol. It is shown that the sorbent provides quantitative isolation of all 23 studied compounds not only from aqueous solutions, but also from milk, bypassing the deproteinization stage. The determination is carried out by HPLC-tandem mass spectrometry using matrix calibration. The detection and determination limits of quinolones are 0.012–0.12 and 0.04–0.4 μg/L, respectively, which are below their maximum residue levels in milk.