Detection of pyrrolizidine alkaloids in commercial honey using liquid chromatography-ion trap mass spectrometry

Pyrrolizidine alkaloids (PAs) are known secondary plant metabolites which can cause hepatotoxicity in both humans and livestock. PAs can be consumed through the use of plants for food, medicinal purposes and as contaminants of agricultural crops and food. PA contaminated grain has posed the largest health risk, although any PA contamination in our food chain should be recognised as a potential health threat. For this purpose, retail honeys were tested by LC-MS/MS. The method allows for specific identification of toxic retronecine and otonecine-type PAs by comparison to reference compounds via a spectral library. In total, 50 honey samples were matched to the reference spectra within a set of tolerance parameters. Accurate data analysis and quick detection of positive samples was possible. Positive samples contained an average PA concentration of 1260 μg kg^-1 of honey. Good linear calibrations were obtained (R² > 0.991). LOD and LOQ ranged from 0.0134 to 0.0305 and 0.0446 to 0.1018 μg mL^-1, respectively.