Determination of Zinc, Iron, Nitrogen and Phosphorus in Several Botanical Species of Medicinal Plants

The total concentration of zinc, iron, nitrogen and phosphorus, as well as their water and acetic acid extractable forms – nitrate nitrogen, ammonium nitrogen and phosphate phosphorus – were determined in st. John’s wort herb (Hypericum perforatum l.) yarrow herb (Achillea millefolium l.), nettle leaves (Urtica dioica l.) and birch leaves (Betula pendula roth.), collected from four natural locations in northern Poland. The content of total zn and Fe was determined by FAAs, whereas of total n, total P and their extractable forms by uV/Vis spectrophotometry. The obtained results showed that particular plant species differed significantly in the contents of zn, Fe, P and P-Po4. The area of harvest didn’t have major effects on the concentration of analyzed elements in the studied plant species. significantly, 13 inter-element correlations were obtained for the studied elements, mainly between iron and nitrogen, iron and phosphorus, phosphorus and nitrogen and among their water-extractable forms, indicating their involvment in metabolism of medicinal plants. nutritional and toxicological aspects of the analyzed plants used commonly as folk medicines in Poland were evaluated by comparison of the obtained results with the WHo/FAo norms.