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EN ISO 10993-7

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EN ISO 10993-7

EN ISO 10993-7 is a standard published by the International Organisation for Standardisation (ISO) and adopted by the European Committee for Standardisation (CEN), entitled „‘Biological evaluation of medical devices – Part 7: Ethylene oxide sterilisation residues’, i.e. ‘Biological evaluation of medical devices – Part 7: Residues from ethylene oxide sterilisation’. The current base text, ISO 10993-7:2008 + A1:2022, has been adopted at European level as EN ISO 10993-7:2008+A1:2022.

The standard specifies the maximum permissible levels for residues of ethylene oxide (EO), ethylene chlorohydrin (ECH) and ethylene glycol (EG) in medical devices that have been sterilised with ethylene oxide (EO), as well as the methods for determining these residues. The limits are determined on the basis of the product’s contact time (limited, long-term, permanent) and the patient group (adults, children).

The standard contains three normative analytical appendices for the determination of residues:

  • Appendix A (normative): Determination of EO and ECH – headspace gas chromatography
  • Appendix B (normative): Determination of EO and ECH – Liquid-injection gas chromatography (extraction method)
  • Appendix C (normative): Determination of EG and ECH – gas chromatography following derivatisation

Application of Annex B: Annex B is based on the extraction of EO and ECH from the appliance using a suitable solvent and the introduction of the extract into the GC by liquid injection. It may be preferred in cases where the headspace method described in Annex A is not suitable (e.g. EO bound to the matrix, devices where sufficient sensitivity cannot be achieved in the headspace, certain polymeric materials). Annex B is not presented as an alternative to Annex A, but as an equivalent normative method.

Why is it carried out?

EN ISO 10993-7 Annex B is applied for the following scientific and regulatory purposes:

  • Ensuring patient safety: demonstrating that EO and ECH residues in medical devices sterilised with EO are within the permissible limits
  • MDR compliance: Provision of the necessary data for EO sterilisation and the assessment of residues in accordance with the EU Medical Devices Regulation (2017/745)
  • Compliance with FDA regulations: Submission of residue data in accordance with ISO 10993-7 for 510(k) and other applications for products sterilised using ethylene oxide
  • Integration into sterilisation validation: carrying out residue assessment as part of validation and routine monitoring in accordance with ISO 11135 (EO sterilisation)
  • Validation of aeration processes: Determining the required aeration duration to reduce EO/ECH residues to a safe level
  • Product and packaging development: Assessment of the influence of material, packaging and sterilisation conditions on the residue profile
  • Routine quality control: assessment of production batches for residues prior to market launch
  • Choice of analytical method: the possibility of determining residues using an equivalent standard method (Annex B) if the headspace method (Annex A) is not suitable
  • Evidence-based approach: A contribution to the holistic assessment of the product’s biological safety in conjunction with ISO 10993-1, ISO 10993-17 and ISO 10993-18

ISO 10993-7 Annex B covers only EO and ECH residues; EG (ethylene glycol) and other residues must be determined in accordance with Annex C or the relevant methods. The results should be evaluated in conjunction with the sterilisation validation, aeration processes and other biocompatibility data.

At NanoTest, we carry out the determination of EO and ECH residues in accordance with EN ISO 10993-7 Annex B, applying scientific rigour within the framework of our accredited laboratory infrastructure and our quality management system.

Please feel free to contact NanoTest for information on method selection, validation, extraction strategy, sample preparation, the testing schedule and the reporting processes for your EO and ECH residue determinations in accordance with EN ISO 10993-7 Annex B.

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