Extractables are compounds forcibly extracted from individual device components using a range of solvents in conjunction with a number of extraction techniques. The observed compounds are potential leachables, although generally found at much higher levels than in a leachable study. The information is then used to create a library for use in the leachable study.
Controlling the extractables will therefore affect the levels and types of leachables observed.
The source of extractable compounds can usually be traced to the raw materials used in the device component manufacture. Experience of handling and analyzing raw materials is a significant advantage in extractable studies.
The planning of an extractable study has to anticipate the leachable study and how the device will be used.
As such, before starting an extractable study, consider the following:
- The analytical sensitivity required
- What scientific instrumentation should be used
- How should the extract be prepared
- Should all the extractables observed be fully identified and quantified?
We follow the PQRI guidelines to evaluate extractables and leachables, based on 3 concepts. With reference to these guidelines and our vast experience, we recommend that an extractable study include:
- Vigorous extraction, multiple solvents, varying polarity
- Multiple extraction techniques
- Multiple analytical techniques
- Extraction methods should be optimised when considering how the component is used
- As the analytical evaluation threshold (AET; from the PQRI) determines the sensitivity requirements, quantitative analysis needs to carefully considered
As devices and their components can cover a very broad range of applications, we would strongly recommend discussing your specific requirements.