In-line solid-phase extraction preconcentration in capillary electrophoresistandem mass spectrometry for the multiresidue detection of quinolones in meat by pressurized liquid extraction

We have developed and validated a CE-MS/MS method using an in-line SPE device (analyte concentrator, AC) to determine eight quinolones of veterinary use whose maximum residue levels in animal edible tissues are established by the EU Council Regulation 2377/90, i.e., danofloxacin, sarafloxacin, ciprofloxacin, marbofloxacin, enrofloxacin, difloxacin, oxolinic acid, and flumequine. Different parameters affecting the AC performance, such as its design (in this case frit-free), the kind of sorbent (Oasis (R) MCX), sample pH, volume, and composition of the elution plug and injection time were studied. The method was validated using standard solutions obtaining LODs between 17 and 59 ng/L. Finally, a pressurized liquid extraction (PLE) method was developed to determine these antibiotics in chicken muscle samples. The whole analytical method was validated in terms of linearity (r(2) > 0.992), recoveries (63-112%), repeatability and intermediate precision (RSD < 20%), LODs (40-140 ng/kg) and LOQs (130-4-70 ng/kg), showing the usefulness of the combination of in-line SPE-CE-MS/MS with PLE for the identification and simultaneous quantification of eight regulated quinolone antibiotics in chicken muscle at very low concentration levels.