Abstract:

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of five pyrrolizidine alkaloids (PAs) (monocrotaline, senkirkine, retrorsine, seneciphylline and senecionine) in honey. The honey samples were dissolved in 0.1 mol/L hydrochloric acid solution and a strong-cation exchange column was used to purify and concentrate the target analytes. The separation of the analytes was carried out on a Phenomenex C₁₈ column(100 mm×4.6 mm, 2.6 μm)using the mobile phases of acetonitrile and 5 mmol/L ammonium acetate-0.1% (volume percentage) formic acid aqueous solution with gradient elution. The separated compounds were detected in multiple reaction monitoring (MRM) mode via positive electrospray ionization (ESI⁺). The calibration curves were of good linearity in the range of 1-100 μg/L (r >0.99). The limit of quantification of the method was 1.0 μg/kg. The average recoveries were between 73.1% to 107.1% at three spiked levels (1, 20 and 50 μg/kg) with the relative standard deviations(RSDs)in the range of 4.1% to 17.0%. The proposed method was applied to different kinds of honey from China, New Zealand, Spain and Australia. The samples included rape, vitex, sunflower, cotton, tilia tree, date, acacia, buckwheat, manuka and eucalyptus honey. Monocrotaline, senkirkine and retrorsine were not detected in the collected honey samples. However, seneciphylline and senecionine were found in most of the honey samples. The concentrations of seneciphylline and senecionine were 11.0-31.1 μg/kg and 8.3-29.1 μg/kg, respectively.

Key words: honey, liquid chromatography-tandem mass spectrometry (LC-MS/MS), pyrrolizidine alkaloids (PAs)