INTRODUCTION. Herbal drugs can often be difficult to identify and distinguish from morphologically similar species, especially when fractionated. For the analysis of complex mixtures of herbal origin, it is reasonable to use additional identification methods, including hierarchical clustering of herbal drugs by their trace element content.AIM. This study aimed to assess the possibility of using hierarchical clustering by trace element content for complex biological matrices (plant mixtures), with officinal chamomile species as a case study.MATERIALS AND METHODS. Multiple morphologically similar species grow together with officinal chamomile species that are widely used in medical practice. The study examined the flowers and peduncles of Matricaria recutita L., Tanacetum parthenium (L.) Sch.Bip., Leucanthemum vulgare Lam., Tripleurospermum inodorum (L.) Sch.Bip., and Matricaria suaveolens Buchenau, as well as artificial mixtures of chamomile with adulterant species (as samples non-compliant with pharmacopoeial specifi ca tions). The content of trace elements was determined by inductively coupled plasma mass spectrometry (ICP-MS). The statistical treatment of the results used Statistica 10 software with a built-in data analysis algorithm for multivariate experiments.RESULTS. Having determined the content of 56 trace elements, the authors plotted a hierarchical cluster tree using cluster analysis methods. M. recutita and M. suaveolens were shown to be the closest to each other in terms of their trace element status, which correlated with their taxonomy. Artificial plant mixtures formed intermediate clusters that were observed between different chamomile species. Moreover, according to the criterion of dissimilarity, the trace element cluster of M. recutita significantly differed from the trace element clusters of all the adulterant species and mixtures containing more than 10% of the adulterant species.CONCLUSIONS. This study demonstrated the possibility of using hierarchical clustering based on the content of trace elements in a biological object to analyse complex systems, including plant mixtures, and identify differences that may have discriminative value for the quality control of herbal drugs.
