The new approach, based on a technique known as laser absorption spectroscopy, makes it possible to vacuum-check vials on production lines at speeds which would have been impossible before. Vials containing freeze-dried drugs must be maintained in a vacuum, or moisture can get in and wreak havoc with the activity and shelf life of the medicine.
Until recently freeze-dried vials were checked for vacuum using a spark test which would make the glass glow if a vacuum is present. The time taken to energise the vial was a significant rate-limiting step using this method, particularly if amber vials were being used.
Using laser absorption spectroscopy, light from a near-infrared semiconductor laser is tuned to match the internal vibrational frequency of a target molecule, such as water or oxygen. When the light is passed through the headspace region of a container, the target molecules absorb energy and they begin to vibrate.
This laser absorption signal is detected using a technique known as frequency modulation spectroscopy (FMS). This provides information about the headspace gas concentration and total headspace pressure.
Using FMS, the absolute pressure or vacuum level in a pharmaceutical container can be measured by looking at either water vapour or oxygen absorption.
Bonfiglioli has designed a new machine, known as the LVA, that uses LAS and FMS to vacuum check vials and can handle rates up to 400 counts per minute (CPM), with semi-automatic models for laboratory use also available. A printer is also installed for printing test results and parameters. The system can handle vials up to 150ml and they may be either amber or transparent.
Blister pack tester
Meanwhile Bonfiglioli has also introduced a new leak tester for blister packaging that provides a clean alternative to methylene blue dye testing.
Methylene blue is effective but is messy, destroys the package being tested and requires human intervention. Bonfiglioli has introduced a compact machine - the BLI - that can detect cracks in the blister of as little as 3 microns across.
The device is fed from a stack of blister packs, with each in turn inserted into a testing chamber using a 'pick and place' mechanism. Sensors analyse the swelling of each blister cell when applied under vacuum and will reject faulty leaking blister packs.
The output can be as high as 600 counts per hour (CPH), which makes it ideal for non-destructive testing of expensive drugs, according to Bonfiglioli.