1. Q3D Elemental Impurities - Guidance for Industry (2015) U. S. Department of Health and Human Services, Food and Drug Administration, Center for Drug Evaluation and Research (CDER), Center for Biologics Evaluation and Research (CBER), pp 3–16. https://www.fda.gov/downloads/drugs/guidances/ucm371025.pdf. Accessed 31 May 2021
2. International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) Q3D on elemental impurities (2017) EMA/CHMP/QWP/115498/2017 Committee for Medicinal Products for Human use (CHMP), pp 3–16. https://www.ema.europa.eu/en/documents/scientific-guideline/implementation-strategy-ich-q3d-guideline_en.pdf. Accessed 31 May 2021
3. Guideline on the Specification Limits For Residues of Metal Catalysts or Metal Reagents (2008) European Medicines Agency, London, Doc. Ref. EMEA/HMP/SWP/4 446/2000, pp 5–9. http://www.ema.europa.eu/docs/en_GB/document_library/Scientific_guideline/2009/09/WC500003586.pdf. Accessed 31 May 2021
4. PH. EUR, Policy on Elemental Impurities - Clarification for Products Outside the Scope of the ICH Q3D Guideline (2015), Strasbourg, France, pp 1–2. https://www.edqm.eu/sites/default/files/press_release_elemental_impurities_pheur_2015.pdf. Accessed 31 May 2021
5. Guédon D, Brum M, Seigneuret JM, Bizet D, Bizot S, Bourny E, Urizzi P (2008) Impurities in herbal substances, herbal preparations and herbal medicinal products, IV. Heavy (toxic) metals. Nat Prod Comm 3(12):2107–2122. https://doi.org/10.1177/1934578X0800301232