Comparative Analysis of Heavy Metal and Arsenic Content in Various Herbal Dosage Forms Marketed in Russia

Abstract

The inclusion of requirements for independent determination of arsenic, cadmium, mercury, and lead, and the current sample preparation techniques into the State Pharmacopoeia of the Russian Federation (Ph. Rus.) requires the revision of the existing limits for elemental toxicants in herbal substances and herbal medicinal products produced from them.The aim of the study was to analyse the data on elemental toxicant content obtained during quality control of herbal substances (herbs, medicinal herb mixtures, extracts, and tinctures) using current test methods and sample preparation techniques, and to compare the obtained results with the Russian and foreign scientific and specialist literature.Materials and methods: the internal data on the content of critical heavy metals and arsenic in different dosage forms of herbal medicinal products, which were obtained by inductively coupled plasma mass spectrometry after sample preparation by decomposition in closed vessels, were compared with literature data. Results: it was demonstrated that the content of lead, cadmium, and mercury in all the test samples did not exceed the Ph. Rus. limits and was consistent with the analysed literature. The arsenic content in some herbal medicinal products was higher than the established Ph. Rus. limits, but complied with the less stringent Ph. Eur. and USP requirements for herbal substances. The authors investigated the link between the content of elemental toxicants and the place of collection and the part of the plant being tested. It was shown that different types of medicinal plants had a tendency to accumulate particular elements. The authors determined the content of the elements to be controlled in extracts and tinctures. The differences in the Russian and foreign requirements for the content of elemental toxicants may be attributed to the method of obtaining experimental data that form the basis for the setting of limits.Conclusions: the results of the study confirm the validity of the existing limits for elemental toxicants in herbal medicinal products. The authors demonstrated the need to revise the existing limits for arsenic in herbal medicinal products.