Survey of pyrrolizidine alkaloids in teas and herbal teas on the Swiss market using HPLC-MS/MS

Pyrrolizidine alkaloids (PAs) are a large class of natural compounds amongst which the esterified 1,2-unsaturated necine base is toxic for humans and livestock. In the present study, a method was developed and validated for the screening and quantification of nine PAs and one PA N-oxide in teas (Camellia sinensis (L.) O. Kuntze) and herbal teas (camomile, fennel, linden, mint, rooibos, verbena). Samples were analysed by HPLC on a RP-column, packed with sub-2 mu m core-shell particles, and quantified using tandem mass spectrometry operating in the positive electrospray ionisation mode. These PAs and some of their isomers were detected in a majority of the analysed beverages (50/70 samples). In 24 samples, PA concentrations were above the limit of quantification and the sum of the nine targeted PAs was between 0.021 and 0.954 mu g per cup of tea. Thus, in some cases, total concentrations exceed the maximum daily intake recommended by the German Federal Institute for Risk Assessment and the UK's Committee On Toxicity (i.e. 0.007 mu g kg(-1) bw).