Chemical Characterization


Nelson Labs Europe’s Extractables and Leachables testing for Medical Devices

Set up of chemical characterization testing

The importance of chemical characterization testing for Medical Devices has been described in the ISO 10993-1 standard of 2009: “Biological evaluation of Medical Devices - Evaluation and Testing within a Risk Management System. In this document, it was pointed out that the identification of material chemical constituents and consideration of chemical characterization (according to the ISO 10993-18 standard) of the materials shall precede any biological testing.

While biological testing on Medical Devices will provide clear pass/fail criteria for the tests performed, the material characterization tests will generate data on the potential chemical compounds that can leach out during the medical use of the device under “worst case” simulation conditions. It is clear that the analytical data, generated via a material characterization approach, may need more consideration with regard to the toxicological impact during the use of the device.

Based on its actual relevance, a consortium of Notified Bodies has elaborated a “Code of conduct” as an awareness campaign for medical device manufacturers to file its technical documentation, if necessary combined with analytical testing (Extractables studies).

The basic elements that need to be considered when making up a Material Characterization Study for Materials used in the manufacture of a Medical Device, are:

  • Selection of the extraction conditions (ISO 10993-12)
    • Extraction Times
    • Extraction Temperatures
    • Extraction Vehicles
  • Analytical Equipment used
  • Initial Toxicological Assessment via a Threshold Approach
    • Setting Allowable Limits for migration compounds, based upon a TTC principle
    • How to translate TTC’s into analytical limits for evaluation
    • How to deal with the semi-quantitative nature of chromatographic “screening” tests
    • Consequences of the defined TTC levels on the required analytical sensitivity


Although a Material Characterization study may initially be an exhaustive exercise for the applicant, there are a lot of advantages that may arise once the study is completed:

  • It will allow creating a database of materials that may be used in other Medical Device applications.
  • Changing the composition of a material for a Medical Device may limit the amount of biocompatibility work, needed to document this change.
  • Changes in the intended use of a material (e.g. type of body contact, contact duration…) may be performed with a different TTC approach on the same analytical data.


Polymer impurities, migrating from the Device into the extraction Vehicle, may come from:

  • Plasticizers, colorants, antioxidants, lubrificants
  • Production products e.g. during molding, surface treatment, welding
  • Additives e.g. pigments, inks
  • Potential process contaminants e.g. Cleaning/disinfection/sterilization agents, machine contaminants
  • Degradation products during manufacturing and processing, transport, clinical use and storage.


Polymers may release toxic compounds which can be removed from a medical device by the action of water or other liquids related to the use of the device (ISO 10993-17).

Our Expert Team will assist you with:

  • Designing the right testing strategy for your Device
  • Calculating the Thresholds of Toxicological Concern, relevant for your application
  • Interpretation of data
  • Reporting of data
  • Writing a comprehensive biocompatibility/Material Characterization Risk Assessment report, taking into account the medical/clinical use (amount mg/treatment), exposure time, age, pharmacokinetics etc… These reports are generally accepted worldwide. 



Compendial testing

European Pharmacopoeia

United States Pharmacopoeia

Japanese Pharmacopoeia

Compendial testing comprises all the analytical testing required to prove the identity, efficacy and safety of raw materials intended for medical device use.

These compendial tests are relevant to assess the biocompatibility of the materials because they try to determine the release of toxic compounds under standard conditions in a direct or indirect way.

Pharmacopeial monographs such as the USP/NF, EP and JP provide standardized methods and specifications for raw materials and finished products.


Nelson Labs Europe
Romeinsestraat 12
B - 3001 Leuven
+ 32 16 40 04 84

Mrs. Cindy Claes
Customer Service Medical Device

Nelson Labs Europe | Chemical Characterization