Effective determination of ampicillin in cow milk using a molecularly imprinted polymer as sorbent for sample preconcentration

•A MISPE method has been used for selective preconcentration of AMP from cow milk.•HPLC with UV detection was used for the quantification of ampicillin.•MIPs have been synthetized and characterized by binding and FT-IR studies.•The method allows AMP determination in milk at concentrations required by legislation.

The aim of this study was to prepare molecularly imprinted polymers (MIPs) with ampicillin (AMP) and to evaluate the feasibility of these materials for being used as solid phase extraction sorbent for the selective preconcentration and determination of AMP in cow milk samples. MIPs were synthesized by bulk polymerization using methacrylic acid or methyl methacrylate as monomer and ethylene glycol dimethacrylate as cross-linker at different ratios. Characterization of the MIPs were carried out by Fourier-transform infrared spectrometry. The variables affecting the molecularly imprinted solid-phase extraction (MISPE) procedure were optimized. AMP recoveries were higher than 98%, and RSD less than 7%. A preconcentration factor of 20 was reached, which was sufficient to determine AMP at levels allowed by the EU (4 μg kg−1) in cow milk. The selectivity of the AMP-MIP was evaluated in presence of other structurally related β-lactam antibiotics (amoxicillin, oxacillin, penicillin G).