Extracting L&E Compounds from Large Medical Implants

Martin Perkins

28th August 2015

Andrew Golby, Leachable, Liquid-Liquid Extraction, Medical Implants, Meeting, Organic, Ray Perkins, SBSE, Stir Bar Sorptive Extraction, Twister,


Andrew Golby has drawn our attention to this Twister (Stir Bar Sorptive Extraction) application. It is very interesting for two reasons:

  1. It is a simple, effective approach for the characterisation of leachable organics from medical implants/devices into aqueous based media.
  2. It is a practical illustration of how Twister can be used to identify trace organic compounds from any larger medical devices or components without the need for destructive sample preparation.

It’s worth considering how else to do this.

The only way I can think of is to carry out the extraction of the implant with the aqueous simulant mix (used to leach organics from the implant), then perform a separate liquid-liquid extraction. This would probably require several hundred millilitres of solvent (possibly DCM) followed by a lengthy blow-down to concentrate the analytes. This is not very elegant and would be prone to cross-contamination and solvent artefact concentration.

In comparison, the Twister method is very simple.

  • The implant is placed into a vessel along with 500ml of a simulant mix and a Twister stir bar.
  • The glassware is placed upon a stirrer plate and the stir-bar mixes the simulant for an extended period.
  • At the same time the simulant is leaching organic compounds from the implant, the Twister stir bar is extracting and enriching the organic leachable compounds from the simulant mix.
  • Once the extraction has been performed, the Twister is removed from the vessel, rinsed and blotted dry, then thermally desorbed and the analytes introduced into the column of the GC–MS without having to perform dilution or splitting.

This is a very neat and tidy way of doing this job and is explained very well in this article.

If this sounds interesting, then, if you are attending the Smithers E&L Conference in November 2015, Anatune’s Andrew Golby will be there and very willing to discuss this with you.

If your interest is more immediate, then please give us a call on +44 (0)1223 279210 or email enquiries@anatune.co.uk.