Advantages of molecularly imprinted polymers LC-ESI-MS/MS for the selective extraction and quantification of chloramphenicol in milk-based matrixes. Comparison with a classical sample preparation

A simple and fast selective extraction of the antibiotic chloramphenicol (CAP) from milk (raw milk, skimmed milk, and milk powder) using a molecularly imprinted polymer (MIP) sorbent is described. The method entails a single centrifugation step prior to loading the supernatant onto the MIP cartridge and subsequent elution with a mixture of solvents. CAP was further analyzed by isotope dilution liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) operating in negative ionization acquisition mode. The advantages of the MIP approach were assessed by comparing the data generated from a classical solid-phase and liquid-liquid extractions procedure, previously developed in our laboratory. A better recovery of CAP due to, an enhanced selectivity and a faster turnaround time (18 samples processed within 3 h compared to 8 h with the classical approach) were evidenced when using the MIP cleanup. The analysis of CAP in raw milk was further validated according to the 2002/657/EC European Union criteria for the analysis of veterinary drug residues at the minimum required performance limit (MRPL) of 0.3 mu g/kg, using CAP-d(5) as internal standard. Non-internal-standard corrected recovery values ranged between 50% and 87% over the range of concentrations considered. The decision limit (CC alpha) and detection capability (CC beta) were calculated to be 0.06 and 0.10 mu g/kg, respectively.