Chemical Characterisation: Everything You Need to Know

Understanding the Role of Chemical Characterisation in Medical Devices

Analytical chemistry was something that during my studies in Medicinal Chemistry, I assumed was largely applicable to the field of pharmaceuticals in drug discovery as well as in formulation development. However, my time here at Test Labs has allowed me to delve further into the world of material science and how important that is. Especially for medical device manufacturers in assessing the validity, reliability, functionality and safety of their products to be used in the healthcare setting. Chemical characterisation is a part of that. It is how device manufacturers analyse the materials chosen for their medical device, so they have an understanding of its properties. But it is also part of biocompatibility assessments, which focus more on patient safety and what the biological risks are when a medical device comes into contact with the human body.

What Is Chemical Characterisation?

Chemical characterisation involves identifying the chemical components of a material and the quantities/concentrations of these chemicals. It is important to know what chemicals are present in a medical device to ensure the device is safe for patients, by identifying any chemical interactions and risks that could arise. Chemical characterisation is also important in assessing the biocompatibility of a medical device and identifying the release of any harmful substances during normal use and under simulated conditions. Depending on the type of substances that are being targeted, the analytical technique used will vary. Common methods used for chemical characterisation include GC-MS, HPLC-MS and ICP-MS.

Read more about these techniques in Test Labs article “ISO 10993-18: Chemical Characterisation of Medical Device Materials”.

How Does ISO 10993-18 Guide Chemical Characterisation of Medical Devices?

The ISO 10993 series of standards provide the framework for evaluating the biocompatibility of a medical device to ensure patient safety. As stated in the ISO 10993-1 standard, medical device manufacturers must consider the chemical, physical, toxicological, electrical, morphological and mechanical properties of the materials that they select for their device. Gathering this information of the device components is the first crucial step in the steps involved in completing a biological evaluation and completing a toxicological risk assessment.

Stepwise Approach Under ISO 10993-18

Part 18 of the ISO 10993 series offers guidance on chemical characterisation of medical device materials using a risk management process. The step-wise process within the ISO 10993-18 standard includes the following:

• Establishing the medical device’s configuration, material composition, and clinical use. This can then be compared to any a device that is already clinically established with the same configuration, composition and clinical use.

• If there is no similar device that is already clinically established, the hypothetical worst case chemical release for the device needs to be assessed. The worst-case chemical release is where the entire device composition was to transfer during clinical use. This involves completing an extractables study.

• If after the extractable study on the worst-case chemical release analysis, the risk is still unacceptable (based on exceeding established analytical evaluation thresholds), a leachables study is performed.

• Completing the toxicological risk assessment based on the identified chemical substances from the previous steps.

For more information on what is involved in extractables and leachables testing, see Test Labs article “Extractables & Leachables Testing: Everything You Need to Know” .

Why Is Chemical Characterisation of Medical Devices Important?

Chemical characterisation is a critical part of completing biocompatibility evaluations of a medical device, as part of adhering to medical device regulations like the MDR. The overall end goal is patient safety and chemical characterisation allows manufacturers to identify any substances that could be released from their device during clinical use and what the risks associated with these substances could be. This in turn allows them to select appropriate materials during the manufacturing process.

What Are the Key Requirements for Chemical Characterisation?

Performing a chemical characterisation analysis will require developing a tailored study plan for your medical device. Consideration is taken into the type/class of device, its clinical use and the nature of its contact with a patient, the materials and composition of both the device as well as any packaging used, how it is processed and what is involved in the cleaning and/or sterilisation steps.

The correct solvent and extraction conditions will need to be determined, and the most appropriate analytical technique will need to be chosen in order to establish the correct chemicals and quantities.