Trace analysis of tiamulin in honey by liquid chromatography–diode array–electrospray ionization mass spectrometry detection

A liquid chromatography with diode array or electrospray ionisation mass spectrometry detection (LC–DAD–ESI–MS) method for the determination of tiamulin residues in honey is presented. The procedure employs a solid-phase extraction (SPE) on polymeric cartridges for the isolation of tiamulin from honey samples diluted in aqueous solution of tartaric acid. Chromatographic separation of the tiamulin is performed, in isocratic mode, on a C18 column using methanol and ammonium carbonate 0.1% in water, in proportion (30:70, v/v). Average analyte recoveries were from 88 to 106% in replica sets of fortified honey samples. The LC–ESI–MS method detection limits differ from 0.5 μg kg−1 for clear honeys to 1.2 μg kg−1 for dark honeys. The developed method has been applied to the analysis of tiamulin residues in multifloral honey samples collected from veterinary treated beehives.