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Pyrrolizidine alkaloids in herbal teas (P1412-RT)

PROOF-ACS organised and performed a ring test on pyrrolizidine alkaloids in chamomile tea and mixed herbal tea in September 2014.

Approximately 600 pyrrolizidine alkaloids (PAs) are known as secondary metabolites in plants worldwide. Especially plants of the families Boraginaceae, Asteraceae and Fabeceae are known to contain PAs. The German Federal Institute for Risk Assessment (BfR) published data on an analytical method for the quantification of 17 PAs in plant material in 2013 (http://www.bfr.bund.de/cm/343/bestimmung-von-pyrrolizidinalkaloiden.pdf). By applying this method to different kinds of teas and herbal teas the BfR identified a contamination of tea and herbal tea products by means of different PAs. Mixed herbal teas, fennel teas and chamomile teas may show comparably high concentrations of PA.

Two test materials (50 g each, powder) were provided in the ring test:

  • Mixed herbal tea spiked with eight PAs:
    Heliotrine-N-oxide, Lasiocarpine-N-oxide, Monocrotaline-N-oxide, Retrorsine, Retrorsine-N-oxide, Senecionine, Senecionine-N-oxide, Seneciphylline-N-oxide

  • Chamomile tea spiked with five PAs:
    Retrorsine-N-oxide, Senecionine, Senecionine-N-oxide, Seneciphylline, Seneciphylline-N-oxide

Neither the number nor the identity of the spiked PAs was announced in advance. However, the scope of PAs covered by the test was specified as a selection of the 17 PAs published in the analytical method of the BfR. The PAs were spiked within a concentrations range recently published for herbal and chamomile teas.

Each participant received a report after the evaluation of the analytical results.
The report contains an assessment on:

  • the identification of the spiked pesticides,
  • the correct quantification with respect to the 
    trueness criterion (70-120 % recovery of the spiked level), and
  • the correct quantification with respect to the 
    comparability criterion (z-score ≤ |2|).

A summary of the report is available here

Time schedule:

  • Dispatch of samples:
    September 15, 2014
  • Sample arrival (in the laboratory):
    September 16/17, 2014
  • Deadline for reporting results:
    September 30, 2014

The participation fee was 950 EUR, blank materials were available at a price of 70 EUR each.