Report on the 2016 proficiency test of the European Union Reference Laboratory for Mycotoxins, for the Network of National Reference Laboratories : determination of cintrinin in of tropane alkaloids in tea and herbal infusions

Tropane alkaloids (TAs) are toxins found in a wide variety of plant species growing in mild climates. The most well-known are Datura, Atropa and Hyoscyamus sp., belonging to the Solanaceae family. The TAs family comprises more than 200 compounds, of which atropine and scopolamine are the most active producing anticholinergic symptoms (e.g. blurred vision, dry mouth, muscle spasms, tachycardia and death) if ingested in toxic quantities. The presence of botanical impurities (e.g. seeds, leaves and roots) has been reported in a variety of tea and herbal blends, stressing the need to control the quality of these products in the EU market. The European Union Reference Laboratory (EURL) for Mycotoxins organised a proficiency test (PT) on the determination of TAs (atropine and scopolamine) in tea and herbal infusions upon request from DG SANTE. The measurand levels were targeted to provide insight on the measurement capabilities of EU Member States' laboratories at concentrations close to the recommended limit of quantification (LOQ) established by the Commission Recommendation 2015/976 (preferably below 5 μg/kg and not higher 10 μg/kg). Additionally, the ratio of atropine to scopolamine was kept as native in the plant materials in some samples. Three matrices appropriately processed were provided to the participants: black tea, peppermint leaves and fennel seeds. The concentrations of atropine varied from 8.3 to 42.2 μg/kg while those of scopolamine ranged from 1.5 to 20.8 μg/kg. The participants were asked to determine atropine and scopolamine in 6 contaminated samples (2 per matrix) and 3 blank materials spiked by them with a TAs solution of unknown concentration. This setup was also aimed to allow a preliminary assessment of the robustness of the EURL-developed method. Thirty-three laboratories from 11 Member States joined the PT, with a very significant participation from Germany. The performance of the laboratories was assessed using zscores with regard to the assigned values obtained by exact matching double isotope dilution mass spectrometry (EMD-IDMS), in line with the ISO 13528:2015. In all cases, the consensus values derived from the participants' data were within the range of the assigned values, considering the respective confidence intervals. On average, eightyseven percent of the z-scores for atropine and 84 % for scopolamine fell in the acceptable range ( z ≤ 2). The success rate varied from 83 to 94 % for atropine and from 67 to 94 % for scopolamine, across the distributed matrices and concentration levels. The robust standard deviations of the reported results for both TAs were in good agreement with the target standard deviation (22 %). The results of this PT indicate that EU Member States' laboratories can determine atropine and scopolamine reliably in tea and herbal infusions at levels relevant to the current legislation (Commission Recommendation 2015/976).