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    Micro-CT Examination of Seal Integrity in Glass Vials

    Closure systems for glass vials containing parenteral pharmaceuticals are critical for protecting the contents against microbial or other environmental contamination. The most common closure system consists of an elastomer stopper held in place by a crimped aluminum band. Compression is applied during the sealing process, which can affect the closure integrity. We examined a series of parenteral vials with our SkyScan 1275 desktop micro-CT to obtain detailed information regarding the position of the elastomer stopper and aluminum band before and after the sealing process of the vials. This information can be used to evaluate the closure integrity and determine if changes need to be made to the sealing process to ensure the integrity of the closure. Synopsys Simpleware software was used to accurately model and analyze the micro-CT data as part of a joint project with Micro Photonics.

    Micro-CT Scan of Parenteral Vials

    Our micro-CT visualization of this series of parenteral vials allows us to examine the effects of capping machine processing conditions on the location and thickness of the rubber stoppers. As can be seen in Figure 1 above, a typical parenteral vial contains either a plastic or glass vial, a polymeric stopper, and a metal crimp seal band.

    Figure 2: Clipped view through the central axis of the vials showing fully uncrimped (top) and crimped views after passing through the capping machine.

    As can be seen in Figure 2, micro-CT imaging is able to draw out differences between the crimped and uncrimped samples. We can observe both the thickness of the rubber and the shape of the aluminum ferrule change after capping. Using this method, vials can be pulled from lots passing through the capping machine under different processing conditions and compared directly to one another.

    Figure 3: Effect of capping on the shape of the rubber with pre-capping in red and post-capping in a green outline.

    Moving to a more advanced image-based analysis program allows us to draw even deeper conclusions than the qualitative changes we can see after imaging. For this work, we collaborated with the team at Synopsis to utilize their Simpleware ScanIP software to provide detailed information on changes arising from the sealing process. Figure 3 demonstrates an overlay of the open and closed positions of the rubber stopper before and after sealing the vial. It is clear the stopper both expands outward to the edges of the glass vial while also driving deeper into the neck of the vial.

    Figure 4: Effect of capping on the shape of the aluminum ferrule with pre-capping in red and post-capping in a green outline.

    Similar to what we observed for the stopper, Figure 4 demonstrates an overlay of the open and closed positions of the aluminum ferrule before and after sealing the vial. Primarily, the metal band is seated onto the vial with the bottom edge curled under the lip of the vial to hold the seal closed.

    Figure 5: Color map representation of deviation to the rubber stopper arising from the sealing process.

    In addition to visualizing and overlaying the changes observed from the closure components during sealing, Simpleware brings the ability to create quantitative color coded images highlighting the deviation of the rubber stopper from its open to closed states, as seen in Figure 5. As we observed in the reconstructed micro-CT images, most of the movement of the rubber stopper occurs at the horizontal edge of the sample as the stopper expands to cover the vial opening; this is visually confirmed by the red coloration showing expansion in the model.


    With advances in the hardware leading to shorter acquisition times, Micro-CT is particularly useful in non-destructive examination of many products allowing for manufacturing process changes to be studied. We hope you found this Image of the Month informative. If you have an Image of the Month sample that you would like us to scan, please contact us by calling Seth Hogg at 610-366-7103 or e-mailing

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    This scans were completed on our high speed desktop SkyScan 1275 system at the Micro Photonics Imaging Laboratory in Allentown, PA. Reconstructions were completed using NRecon and visualization of 2D and 3D results were completed using CTVox.



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