The blurb – a phrase covering anything from “dust cover blurb” over “Information”, “Jacket Text” to “Material”. And a word that summarises many aspects of DIN EN ISO 10993-18:2021-03 in one term. How come? Well, the Biological evaluation of medical devices – Part 18: “Chemical characterisation of materials for medical devices in the context of a risk management system” is more than just filing a material data sheet. Together with our partner, Hohenstein Medical, we would like to introduce you to the requirements of this standard and other standards in the EN ISO 10993 series.

The ISO 10993 series of standards covers various aspects of the biological assessment of medical devices and makes an important contribution to demonstrating the safety of a medical device. It is applicable when the material or medical device comes into direct or indirect contact with the body (categorisation according to ISO 10993-1).

In principle, manufacturers must assess the risks of the substances that could reach the patient. See also more of our articles on this topic:

If the starting materials are known and are also no longer changed by further production processes, no further tests may be necessary.

In most cases, however, relevant changes are still made in the production process. Examples are thermal stress, polymerisation, gluing, or even a sterilisation process. In addition, the product should be evaluated over its lifetime. Therefore, ISO 10993-18: Chemical characterisation of materials for medical devices is often to be consulted as part of a risk management system.

It describes a method to identify and quantify the chemical components of a medical device and thereby assist manufacturers and material suppliers in biological evaluation. Chemical characterisation can also be used for degradation products (further information on other aspects of degradation product evaluation is described in ISO 10993-9, ISO 10993-13, ISO 10993-14 and ISO 10993-15).

Hohenstein Medical, which specialises in testing, certification and research into textile products, regularly supports us with its expertise in carrying out these tests. Since 2020, we have been cooperating closely and regularly in the testing of products. Public examples of our cooperation are:

In projects, we as seleon use the biological evaluation plan to pave the way for a sensible testing strategy, which we can detail and implement in cooperation with the experts from Hohenstein. The commissioning manufacturers benefit from this.

Hohenstein Medical presents itself and its methodology

As an accredited testing laboratory and reliable partner, we support companies along the entire value chain in successfully bringing their products to market. Neutral proof of the effectiveness and safety of the products is essential for this. As a testing institute and research partner, we see ourselves first and foremost as a solution provider and always enter into dialogue with customers and support them with interdisciplinary knowledge, also with individual testing methods outside of common testing standards.

Cooperation with seleon from the perspective of Hohenstein Medical

The cooperation always works smoothly and we perceive seleon as a very open and professional partner. The exchange always takes place at eye level and the different competences of our companies complement each other well so that we can optimally support our customers. Of course, this applies in both directions.

Product types and product classes for which Hohenstein offers chemical characterization

Chemical characterisation according to DIN EN ISO 10993-18 can in principle be carried out for any medical device, but our experience is primarily in the broad field of Class 1 medical devices. Due to our company history, we currently mainly test textile products, but the tests are also designed for all other types of materials, so we have no restrictions here.

Determination of the necessary sample preparation and extraction

The application and intended use of the product is also decisive here.

For this, we first need several pieces of information from our customers:

  • What material is the product made of?
  • Which surface is in contact with the patient/user?
  • How long is the contact time?

At the beginning, the client receives an order data sheet on which he can note the information known to him. If the data contained therein is not yet sufficient, a new consultation takes place. If, for example, a product is too large and needs to be cut up for extraction, it is advantageous if the customer prepares this accordingly.

Which sample preparation is suitable in each case is clarified with the customer in advance.

Basically, Hohenstein Medical offers extraction in methanol and n-hexane. In addition, there are other extraction options – Annex D of the standard provides an overview of the solvents commonly used for the extraction of polymeric medical devices/materials in Table D1:



Polarity index





Dimethyl sulphodixe












n-Propyl alcohol


i-Propyl alcohol













However, the extraction options we offer represent a worst-case scenario. If other extractions are required, we will of course address this and advise on the methodological feasibility.

An example from everyday life: An extraction in aqueous solution is requested, which can only be analysed using a head space method. Unfortunately, certain substances, such as plasticisers, cannot be detected because they do not pass into the gas phase used for analysis. Our recommendation is therefore not only to select a solvent according to its application, but also to consider the worst-case scenario.

Do you prepare reports including toxicological evaluation?

No, the report is prepared by Hohenstein Medical in the form of a list of detected substances whose extractable amount is above the AET (= Analytical Evaluation Threshold). An evaluation is not carried out. If the customer is unable to evaluate the present values with regard to his medical device on his own, he must subsequently consult a suitable toxicologist.

Chemical characterisation under the MDR

You are now wondering to what extent this standard is also applicable to your medical device with a low risk class? So far, you are used to picking the applicable tests based on the overview table of ISO 10993-1 as well as contact type and duration and testing them out separately? In this case, we advise you to take a look at the General Safety and Performance Requirements, Requirement 10 in Annex I of the MDR. If you would now like to rethink your test strategy, Hohenstein Medical as a test service provider and seleon GmbH as competent advisors will be happy to assist you. So that the blurb fits properly in the end.

Please note that all details and listings do not claim to be complete, are without guarantee and are for information purposes only.