Total and extractable iron in selected herbs collected from natural areas in Northern Poland
The concentration of total iron and iron (II ) extracted by hot twice distilled water was analyzed in following medicinal plants collected from natural areas: St Johns wort (Hypericum perforatum L.), yarrow (Achillea millefolium L.), nettle (Urtica dioica L.) and birch (Betula pendula Roth.). Total iron was determined by FAAS method after microwave mineralization of samples, whereas Fe (II ) was extracted by twice distilled water in temperature of 85oC and determined spectrophotometrically with use of o-phenantroline. The obtained results indicate that total iron content is from several dozen to more than 200 �Ęg/g of dry plant weight and is correlated with plant species. In case of iron (II ) it was determined in amounts ten times less than total concentration of the element. It was noticed that level of that form of iron is positively related to total amount of iron in analyzed medicinal plants. Extremely high concentration of both forms of iron was characteristic for one sample of nettle collected in the Vistula Sand Bar. Based on the conducted research it is possible to state that iron on +2 oxidation state extracted by water can become a source of bioavailable form of this element for human.