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Solvent compatibility for extractables analysis of silicones
Md Shah Alam1, Kanti Sapkota1, Jacob Hill1
1Center for Devices and Radiological Health, US. Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States.
Journal of Pharmaceutical and Biomedical Analysis
|July 30, 2026
Summary
This study addresses challenges in analyzing silicone medical devices by evaluating solvent effects on material degradation and extraction efficiency. Ethanol proved more effective than cyclohexane for extracting compounds from silicone.
Area of Science:
- Materials Science
- Analytical Chemistry
- Biomedical Engineering
Background:
- Silicone rubber is widely used in medical devices due to its unique properties.
- Assessing potential toxicity requires exhaustive extraction and identification of compounds per ISO 10993-18:2020.
- Solvent compatibility with silicones poses analytical challenges, causing swelling and degradation.
Purpose of the Study:
- To explore methods for assessing silicone degradation during chemical characterization.
- To quantify the extraction efficiency of semi-polar versus non-polar solvents.
- To elucidate the extraction kinetics of common extractable species from silicones.
Main Methods:
- Evaluating silicone rubber degradation using swelling ratio and vibrational spectroscopy.
- Assessing polymer network deformation using Hansen solubility parameter and dielectric constant.
- Comparing extraction efficiency and kinetics of different solvents (ethanol, cyclohexane).
Main Results:
- Hansen solubility parameter and dielectric constant are effective indicators of silicone deformation.
- Ethanol demonstrated over 70% greater extraction efficiency compared to cyclohexane.
- Extraction kinetics indicate near-exhaustive extraction of chemicals within 10 hours.
Conclusions:
- Solvent selection is critical for accurate chemical characterization of silicone medical devices.
- Semi-polar solvents like ethanol offer superior extraction efficiency over non-polar solvents.
- Understanding extraction kinetics ensures comprehensive analysis for medical device safety assessment.
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