Study of the content of heavy metals and arsenic in dry extracts from medicinal plant materials of different morphological groups

Introduction. Extraction dosage forms based on medicinal plant materials are very popular for medical use and must meet safety requirements. As part of the harmonization of pharmacopeial requirements, determining the total content of heavy metals in dry extracts is not enough. It is necessary to unify methods for determining heavy metals and arsenic in medicinal herbal preparations.

Objective: to determine the content of heavy metals and arsenic in dry extracts from raw materials of various morphological groups containing essential oils.

Material and methods. The objects of the study were dry extracts of calamus rhizomes, rhizomes with valerian roots, mint leaves and chamomile flowers obtained under industrial conditions. Sample preparation was carried out using microwave decomposition and ashing in a muffle furnace. The elemental composition was determined by inductively coupled plasma mass spectrometry.

Results. The content of 16 elements (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr, Mo, Cd, Sb, Hg, Pb) in the studied extracts was determined. Mercury was not detected in the samples, the concentrations of the 15 elements found were in the range of 0–250 mg/kg, and toxic elements (Pb, Cd, As, Hg) did not exceed 0.233 mg/kg. The largest quantities contained iron and manganese, and the smallest quantities contained chromium, arsenic, lead and cadmium. The maximum number of elements was contained in the studied samples of rhizome extract with valerian roots, the minimum – in the extract of calamus rhizomes. The morphological group of the feedstock and the specific features of the accumulation of elements can play a decisive role. The results of the study are consistent with the literature data. A comparative analysis of two methods for sample preparation of dry extracts showed that microwave decomposition in closed vessels is preferable, in which 24% more elements are quantified than after ashing in a muffle furnace. The possible intake of minerals into the human body when consuming an extract of rhizomes with valerian roots was calculated. It was established that the amount of elements did not exceed the upper permissible levels of daily intake, on the basis of which the studied extracts can be considered safe for medical use.