Molecularly imprinted polymer as in-line concentrator in capillary electrophoresis coupled with mass spectrometry for the determination of quinolones in bovine milk samples

• MIP as sorbent for an in-line solid phase extraction analyte concentrator in CE–MS.
• Determination of eight regulated veterinary quinolones in bovine milk samples.
• Optimization of parameters (sample pH, elution plug and injection time).
• Sample injection with minimum pretreatment and LODs between 3.8 and 4.7 μg kg−1.
• Recoveries ranging from 70.0 to 102.3% and satisfactory relative standard deviations.

In this work molecularly imprinted polymers have been evaluated as sorbent for the construction of an in-line solid phase extraction analyte concentrator in capillary electrophoresis coupled with mass spectrometry for the determination of the eight regulated veterinary quinolones in bovine milk samples. Different parameters affecting the analyte concentrator performance, such as sample pH, volume and composition of the elution plug and injection time, were studied. Sample volumes of 22 μL (2 bar for 15 min) were loaded on the MISPE microcartridge and the retained analytes were eluted by injecting a plug of MeOH/H2O/NH3 (60/37/3 by volume) for 125 s at 50 mbar (60 nL). The proposed method is simple for the monitoring of these antibiotic residues in milk samples, allowing the direct injection of the samples with minimum sample pretreatment, achieving limits of detection between 3.8 and 4.7 μg kg−1 and unequivocal identification of the compounds working in tandem mass spectrometry. Recoveries ranging from 70.0 to 102.3% were obtained and satisfactory intra-day and inter-day RSDs were achieved (≤12% and 15% respectively). Reproducibility among different constructed analyte concentrators showed RSD ≤ 11%.