Multi-screening approach to monitor and quantify 42 antibiotic residues in honey by liquid chromatography-tandem mass spectrometry

A multi-screening approach for monitoring potential chemical contaminants in honey by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) has been developed. A total of 42 veterinary drugs (5 tetracyclines, 7 macrolides, 3 aminoglycosides, 8 beta-lactams, 2 amphenicols and 17 sulfonamides) were surveyed with the ultimate goal of unambiguously confirmed and quantified these analytes at a concentration level of 20 microg/kg. A basic sample preparation including four subsequent liquid/liquid extraction steps was necessary to adequately extract the compounds of interest from the honey. The four extracts were injected into the LC-ESI-MS/MS using a stacking injection procedure. Validation of the entire procedure was carried out according to the European Union directive 2002/657/EC at three concentration levels, i.e., 10, 20 and 30 microg/kg. Good performance data were obtained for 37 analytes, out of the 42 studied. Limit of compliance and detection limit were calculated based on an internal limit set at 20 microg/kg for all the compounds and ranged between 24-30 and 27-80 microg/kg, respectively. A limited survey on honeys of different geographical origins has demonstrated that positive honey samples were often contaminated by more than one class of drugs, thus highlighting the usefulness of such multi-screening approach to ensure and warrants the quality of honey.