Analytical strategies for the determination of pyrrolizidine alkaloids in plant based food and examination of the transfer rate during the infusion process

Two sample preparation methods were developed (graphitised carbon and C18 solid phase extraction clean-up) and validated in house using liquid chromatography and tandem mass spectrometry (MS/MS) for the determination of 30 pyrrolizidine alkaloids (PAs) in salads, herbs, tea, herbals teas as well as tea infusion and icetea beverages. Total PAs concentration of samples purchased on the Belgian market varied greatly with matrix type ranging from < LOD to 187151 ng/g for dry samples, while for infusions and ice-tea beverages the highest PAs concentration was 2106 ng/mL. Surprisingly high PAs concentrations were detected in herbs and spices mixes. The infusion study indicated a transfer rate between 16 and 28% (except for monocrotaline) which highlights the overestimation of PAs concentrations in infusions when derived from a dilution factor (transfer rate of 100%) to the measured concentrations of the dry tea sample.