Tylosin A and desmycosin in honey by salting-out assisted liquid-liquid extraction and aqueous normal phase ultraperformance liquid chromatography-tandem mass spectrometry.

A simple and rapid method was developed for the determination of tylosin A and desmycosin residues in honey. Aliquots of honey samples were dissolved in a concentrated solution of sodium acetate and the target analytes were subsequently extracted with acetonitrile. The resulting organic extract was chromatographed under aqueous normal phase (ANP) LC conditions using a bare silica stationary phase with acidified solutions of ammonium formate in both water and 5:95 water: acetonitrile as the mobile phases. Tylosin A and desmycosin residues were measured using MS/MS in the multiple reaction monitoring (MRM) mode. Based on the analysis of replicate honey samples fortified at 5, 20, and 100 μg kg, the method was found to provide high accuracy and precision with average intraday trueness ranging from 90.2 to 111.2% and standard deviations of less than 7%. For spiked replicates fortified at the limit of quantification (1 μg kg), the intraday accuracies ranged from 72.0 to 102.7% for tylosin A and from 72.1 to 93.8% for desmycosin, with standard deviations all lower than 12%. Matrix effects were relatively minimal and consistent between honey samples which eliminated the need to perform any additional cleanup of the sample extracts prior to ANP-UPLC-MS/MS analysis. Graphical abstract.