Pyrrolizidine Alkaloids in Honey Bee Products

摘要

Recently, contamination of honey with pyrrolizidine alkaloids (PA) has been reported as potential health risk. Therefore, it was of interest to develop a reli-able tool for selective and quantitative determination of PA in honey. Sample preparation of the novel method comprises strong cation exchange solid-phase extraction (SCX-SPE), followed by two reduction steps using zinc and LiA1H4 and subsequent trimethyl silylation. During this procedure the major toxic PA are converted into a single necin backbone which is analyzed by gas chromatog-raphy-mass spectrometry (GC-MS) in single ion monitoring mode (SIM). The method was applied to 216 commercially available floral honey samples and, after some modifications, to 55 pollen products available as food supplements. Among the honeys 19 samples (9%) contained PA in the range from 0.02 to 0.12 μg g~1' (calculated as retronecine equivalents). Pollen products showed a higher degree of contamination (17 out of 55; 31%) and revealed much higher concentrations compared to honey (amounts from 1.08 to 16.35 pg g~(-1)). For the first time, the present method allows the exact and selective determination of toxic PA by simply detecting a single sum parameter which contains the toxic principle of the PA (1,2-double bond). The method can be applied independ-ently from secondary information such as botanical origin or the oxidation state of the PA (tertiary PA, PA-N-oxides). The values observed - especially in pollen products - provoke the discussion of an international regulation of PA in food.