Vial integrity assurance at low temperature
Storage at ultra-freezer low temperature (from -60° C to -90°C) raises the problem of vial integrity assurance and the need for a specific leak test method.
The foreseeable risk on the guarantee of sealing of the vials depends on glass and stopper elastomer thermal contraction under cooling; in addition, the elastomer at –60°C will be below the glass transition temperature, thus it will have elastic reaction behaviour totally different from Ambient temperature. Eventually, even when the vial is taken from the freezer and left reach room temperature, there is a risk due to the different response of different elements (vial and stopper) to the re-heating, with increased possibility for loss of tightness.
Finally, vials perfectly conform at the time of filling could be leaking during or after cryostorage.
Regulations require to validate that in all phases of stocking and transportation do not occur conditions that could cause contamination. Therefore, a specific method is required. This method should be capable to guarantee that, due to cryoconservation, there are no conditions allowing the ingress of contamination in the vial.
Traditional techniques are not suitable for the purpose or are too time-consuming and labour-intensive. Namely:
Vacuum Decay cannot be done on the samples inside the deep freezer; it only can be done at ambient T to avoid humidity condensation and the frozen liquid can cause false negative.
High Voltage HVLD in a similar way is not compatible.
Helium leak test need expensive equipment and the procedure is laborious and time consuming.
The real cost-effective answer, easy and fast to perform, is available with the Gasporox method, that uses the CO2 content analysis in the vial headspace.
The systems HGA (Headspace Gas Analysis) from Gasporox allow determination of specific gas concentration in the headspace; in this way, the defective closures are detected. The bench-top models can be used in laboratory near the stocking place; in addition, Gasporox offers instruments online for production in pharma, food and beverages, etc. Please contact us for more information.
