Arsenic, cadmium and lead in medicinal herbs and their fractionation

Arsenic, cadmium and lead were determined for quality control monitoring purposes of Bulgarian herbs and their infusions by inductively coupled plasma mass spectrometry and electrothermal atomic absorption spectrometry. Twelve samples of yarrow (Achillea millefolium), 18 of chamomile (Flores Chamomillae), 8 of bearberry leaves (Folia uvae ursi), 24 of peppermint (Mentha piperitae folium), 10 of hibiscus (Hibiscus sabdariffa), 14 of oregano (Origanum vulgare) and 12 of thyme (Thymus serpyllum) were analyzed. The studied toxic elements were present in the medicinal plants (12–225 μg/kg As, 15–268 μg/kg Cd, 0.2–8.6 mg/kg Pb). Arsenic was found in all herbal infusions at levels up to 0.4 μg/l. Cadmium was present in infusions of chamomile, hibiscus, peppermint and thyme at levels up to 0.7 μg/l. Lead was detected only in hibiscus infusions (2–3 μg/l). It was established that the major part of arsenic and lead in herbal infusions existed in biomacromolecular fraction. Cadmium appears to be present mainly in cationic form at pH 1 (stomach acidity), but at pH 7.6 (intestine acidity) there is a non-cationic fraction as well.