What Is Elemental Impurities?
Elemental impurities analysis determines metal impurities that may be present in the product. ICH Q3D classifies elements by toxicity and likelihood of occurrence and defines permitted daily exposure (PDE) limits by route of administration. Measurement is mostly by ICP-MS, with the specimen digested with acid in a microwave.
Purpose of Elemental Impurities
The purpose is to show the product is safe with respect to elemental impurities through a risk-based assessment. ICH Q3D requires a control strategy based on risk assessment, not routine analysis of every element for every product.
Which Products Is Elemental Impurities Applied To?
- Finished dosage forms
- Active pharmaceutical ingredients
- Excipients
- Packaging materials
- Herbal medicinal products
In Which Sectors Is Elemental Impurities Used?
Standards Related to Elemental Impurities
- ICH Q3D(R2) (elemental impurities guideline)
- Ph. Eur. 2.4.20 (determination of elemental impurities)
- Ph. Eur. 5.20 (elemental impurities general chapter)
- USP <232> (limits) and USP <233> (methods)
Elemental Impurities Conditions
- PDE
- The permitted daily exposure is defined in ICH Q3D by element and route of administration
- Risk assessment
- Which elements are analysed is determined by risk assessment
- Digestion
- Closed-vessel microwave acid digestion
- Verification
- The method is verified per USP <233> criteria
Equipment for Elemental Impurities
- ICP-MS
- ICP-OES
- Microwave digestion system
- Acid purification system and clean laboratory area
- Analytical balance
Sample Requirements for Elemental Impurities
- Sufficient specimen quantity
- Daily dose information must be provided — the PDE calculation depends on it
- Packaging material information must be provided
- The specimen must be sent protected from metal contact
Duration of Elemental Impurities
Digestion and ICP-MS measurement together take several working days. Duration extends if the risk assessment and method verification are being done for the first time.
Elemental Impurities Procedure
- 1A risk assessment per ICH Q3D is performed and the element list is determined.
- 2The specimen is acid-digested in a microwave.
- 3Internal standard is added and the specimen is diluted.
- 4Element concentrations are measured by ICP-MS.
- 5Recovery and accuracy checks are assessed.
- 6Results are compared against the PDE based on the daily dose.
Elemental Impurities Acceptance Criteria
ICH Q3D defines permitted daily exposure (PDE) values for each element and each route of administration (oral, parenteral, inhalation). The result is compared against the exposure calculated from the product's maximum daily dose. The acceptance criterion is not given on this page: for every active substance and every product, the limit comes from the relevant pharmacopoeia monograph or the approved specification in the marketing authorisation dossier. The pharmacopoeia's general chapter defines the method; the monograph sets the limit.
Evaluation of Results
The result is assessed not as an absolute concentration but converted to daily dose: the same concentration can exceed the limit in a product with a high daily dose while staying under it in a low-dose product. Source analysis also matters; the impurity may come from the raw material, manufacturing equipment or packaging, and the control strategy is built around the source.
Elemental Impurities Report
- Product identification, batch and maximum daily dose
- Risk assessment and list of elements analysed
- Method applied and verification information
- Result and limit of quantification for each element
- Calculated daily exposure and PDE comparison
Accreditation
EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.
Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.
Scope and authorisationsRelated Regulations
- 2001/83/EC Directive on Medicinal Products for Human Use
- GMP Guide (EudraLex Volume 4)
Pharmaceutical Analysis — What Does This Testing Field Cover?
The section below describes the field that the Elemental Impurities test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.
Pharmaceutical analysis determines the identity, purity, quantity and behaviour of an active substance and of the finished product. What sets this family apart is that the methods are largely defined in PHARMACOPOEIAS: the European Pharmacopoeia (Ph. Eur.) and the United States Pharmacopeia (USP) give both the method and the acceptance framework together.
The binding nature of the pharmacopoeial method shapes how the field works. In other sectors a laboratory can choose a suitable method, whereas here the method in the monograph governs; if an alternative method is to be used, its equivalence must be demonstrated. This is what makes results comparable worldwide.
Analyses are carried out in several groups. Identity and assay (HPLC, UV, titration) show what the product is and how much active substance it contains. The impurity profile and residual solvents look for unwanted compounds arising from the manufacturing process. Elemental impurities address metals originating from catalysts and equipment. Dissolution and disintegration behaviour is the most important in vitro indicator of how the drug will be released in the body.
The DISSOLUTION TEST is one of the most critical measurements in the field. It is not enough for a tablet to contain the right amount of active substance; that substance must dissolve at a suitable rate. The dissolution profile is used to assess the effect of formulation changes on bioavailability and holds a central place in generic drug licensing.
METHOD VALIDATION is a mandatory step in this family. If a pharmacopoeial method is used, it is verified that the method works properly under that laboratory's conditions. If an in-house method has been developed, it is validated against parameters such as linearity, precision, accuracy, specificity, limits of detection and quantification, and robustness. A result produced with an unvalidated method cannot be used in a licence dossier.
Stability studies determine shelf life and are the longest-running work in the field. The product is held under defined temperature and humidity conditions, analysed at set intervals, and the results become the basis of the shelf life and storage condition claims. Accelerated conditions give preliminary information but real-time data is what counts.
The microbiological side is a separate body of work: microbial enumeration, testing for specified microorganisms, sterility testing for sterile products and the bacterial endotoxin test. For sterile products, packaging integrity and sterilisation validation also come into play.
Data integrity has moved to the centre of inspections in recent years. It is not enough for the result to be correct; the raw data must be traceable, unalterable and auditable. Validation of electronic record systems has therefore become an inseparable part of analysis.
Method groups in this field
Identity and assay
HPLC, UPLC, UV-Vis spectrophotometry, titration, identity confirmation by FTIR.
Impurities and residues
Related impurities, degradation products, residual solvents (GC headspace), nitrosamine screening.
Elemental impurities
Determination of elemental impurities by ICP-MS and ICP-OES and the associated risk assessment.
Physicochemical
Dissolution and disintegration, hardness, friability, uniformity of dosage units, water content (Karl Fischer), particle size.
Microbiological
Microbial enumeration, specified microorganisms, sterility, bacterial endotoxin, preservative efficacy.
Stability
Real-time and accelerated stability studies; photostability and in-use stability.
Commonly confused in this field
- The pharmacopoeial method is binding; an alternative method may be used only by demonstrating its equivalence.
- A result produced without method validation cannot be used in a licence dossier.
- Accelerated stability does not replace real-time data; shelf life is supported by real-time results.
- The dissolution profile is sensitive to apparatus type, agitation rate and medium; the conditions must be complete in the report.
- A shortcoming in data integrity produces a non-conformity in an inspection even when the result is correct.
- A change of formulation or supplier requires analytical comparison and, where necessary, a new stability study.
Which decisions these results support
- The licence dossier and batch release
- Determining shelf life and storage conditions
- Method transfer and method validation
- Incoming raw material acceptance control from suppliers
- Assessing the effect of a formulation change on bioequivalence
Related Tests
Frequently Asked Questions About Elemental Impurities
Has this replaced the old heavy metals test (Ph. Eur. 2.4.8)?
Yes, elemental impurity control is now based on ICH Q3D and element-specific measurement. The old colorimetric heavy metals test does not substitute for this approach.
Is analysis required for every element?
No. ICH Q3D calls for a risk-based approach: only the elements with a likelihood of entering the product are assessed. The risk assessment must be documented.