Simultaneous determination of aminoglycosides and colistins in food

A novel method for the simultaneous identification and quantification of twelve aminoglycosides (AGs) and two colistins in meat and bovine milk has been developed. The analysis was carried out using liquid chromatography coupled to quadrupole-Orbitrap mass spectrometry (LC-Q-Orbitrap). Among the HILIC (Hydrophilic Interaction Liquid Chromatography) stationary phases tested, the bare silica Poroshell 120 provided the best results. The samples were extracted with an aqueous solution followed by an SPE clean up based on the weak cation exchange mechanism. The validation study was performed carrying out 72 experiments per matrix at six different concentrations in a range encompassing the Maximum Residue Limits. The recoveries were from 72 to 87% in meat (except colistins) and from 82 to 96% in milk. Repeatabilities and intra-lab reproducibilities were lower than 10 and 15%, respectively. Limits of detection were lower than or equal to 33 µg kg−1. Finally, test materials containing AGs prepared for interlaboratory studies were successfully analysed.