Abstract
Purpose: :
To investigate a novel purification process for removing impurities from silicone oil for use as a vitreoretinal tamponade
Methods: :
Supercritical Fluid Extraction process using CO2 as a solvent was used to extract low molecular weight cyclics and oligosiloxanes from crude silicone oil
Results: :
Size Exclusion Chromatography (SEC) of the SCF extracted oil shows narrowing of the polydispersity to 1.44 from 1.95 for the crude oil. The weight average molecular weight, Mw, increased from about 66,000 for the crude oil to 76,000 for the purified oil. The levels of various oligosiloxanes, as measured by GC/MS, were comparable to the oil produced using commercial process. It was also observed that silicone oil purified using this process had a distinct interfacial tension (32 dynes/cm) between the oil and water phases compared to commercially available product where the tension could not be measured due to near identical densities. This may significantly reduce the possibility of silicone oil emulsification that is likely from increased intermixing of the oil and aqueous phases in the eye.
Conclusions: :
SCF extraction based on CO2 is a cheap, non-toxic and an environmentally friendly process that can be an effective alternative to strong organic solvent based purification processes for removing toxic low molecular weight impurities from silicone oil. Additionally, oil purified using this process may have a reduced tendency to emulsify.
Keywords: vitreoretinal surgery • vitreous substitutes • vitreous