Evaluation of Some Pyrrolizidine Alkaloids in Honey Samples from the Veneto Region (Italy) by LC-MS/MS

Abstract

Pyrrolizidine alkaloids (PAs) are natural toxins, supposed to be converted to hepatotoxic metabolites in the liver of mammalians, and preventing the uptake of PAs is the only way to reduce the attendant health risks. A liquid chromatography coupled to mass spectrometry (LC-MS/MS) method was developed according to the Decision 2002/657/EC, to evaluate the contamination of Veneto honey by the following pyrrolizidine alkaloids: echimidine, heliotrine, lycopsamine, retrorsine, senecionine, and seneciphylline, as well as their N-oxides (pyrrolizidine alkaloid N-oxides (PANOs)). Before the solid-phase extraction, a reduction step with zinc dust in the presence of sulfuric acid was carried out for the reduction of PANOs to PAs in honey samples. For all of the analytes, the mean recovery ranged between 82.70 and 104.16 % and the limit of quantification (LOQ) was 0.25 μg kg−1, fully satisfying the LOQ of 1 μg kg−1 as requested by EFSA (2012). The validated method was applied for the analysis of 60 Veneto samples produced from local beekeepers. Among the samples, 17 % were positive for the PAs monitored, and their total PA contents ranged from 0.6 to 17.6 μg kg−1. In all of the samples, the contribution from the PANOs appeared to be negligible. The total PA contents found in the Veneto honey samples never exceeded the limit of 0.42 μg per day for an individual weighing 60 kg, established by the German Federal Institute of Risk Assessment (BfR) in 2011. These preliminary results provide useful advice to beekeepers for finding the most suitable location for beehives to achieve a substantial reduction of the PAs in honey.