Development and Validation of Procedures for Determination of Elemental Toxicants in Herbal Substances and Herbal Medicinal Products

When the approach to quality control of herbal substances (HSs) and herbal medicinal products (HMPs) changed from determination of the total content of heavy metals by calorimetry to selective determination by spectrometric techniques, many manufacturers of such products failed to meet the new requirements in their registration dossiers. Test procedures submitted by manufacturers often need to be clarified, and validation protocols often lack data.

The aim of the study was to provide recommendations to HS and HMP manufacturers on the choice of test methods, materials, reagents, methods of organic matrix mineralisation, and main validation parameters, as well as recommendations on validation of the procedure for elemental toxicants determination, and preparation of the “Heavy metals and arsenic” part of the regulatory submission.

Materials and methods: the study included analysis and systematisation of scientific literature, requirements of the Russian and foreign pharmacopoeias, guidelines, manuals on instrumental methods of analysis, and first-hand experience in elemental analysis of various types of HSs and HMPs.

Results: the authors formulated recommendations on the choice of sample mineralisation conditions for quantification of elemental impurities in biological products, and substantiated requirements for the reagents, materials, and equipment. The paper compares different methods of elemental analysis. It was demonstrated that the main mistakes made by manufacturers stem from disregard to the organic matrix effect on the measurement results and lack of agreement between the impurity concentration being determined and the range of the calibration curve used. The paper gives acceptance criteria for validation parameters of test procedures for heavy metals and arsenic determination in HSs and HMPs.

Conclusions: it is not correct to use reference standards containing heavy metals as inorganic salts not bound to organic compounds, for HS and HMP analysis. The criteria given in the European Pharmacopoeia and the United State Pharmacopoeia can be used for a number of validation parameters, when they are not included in the Russian Pharmacopoeia.

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