Process

The depyrogenation process varies depending on the technique used, the load type and the product being sterilized. No matter the specifics of your application, Ellab has a flexible solution.

Ellab offers custom made mineral insulated semi-flexible metal sensors. Ellab high temperature sensors withstand exposure to temperatures up to 400°C and can be delivered in custom lengths. Their small diameter and ductile characteristics makes them perfect for measurements inside empty vials and exact positioning in the cold spot. If there are space constraints inside the vessel, double sensors are available.

Monitoring

When monitoring depyrogenation processes, all wireless data loggers need to be protected from the extreme temperatures. Ellab’s thermal barriers offer different levels of protection, depending on the length and temperature of your process so you can optimize space and resources.

Our flat-pack thermal barrier is specially designed to provide high protection in tunnels with little gate headspace, making your study easy to set-up.

For real-time data collection during depyrogenation processes, it is no longer required to use cables. Ellab’s TrackSense Pro SKY system allows for wireless radio transmission of data directly to your PC for documentation and process control.

Challenges

Thermal processes above 150°C may damage the electronics and sensors of monitoring equipment, resulting in the loss of valuable process data. Ellab’s high quality materials provides a reliable validation system. The sterilization of empty glass vials can be a fragile process during the set-up; the vials can be tipped over/broken easily by the movement of thermocouples.

During dry heat sterilization, air is the heat transmitter, which poses specific concerns for correct sensor positioning if a worst-case scenario approach is to be taken. The use of high temperature semi-flex metal sensors minimizes inaccuracies in sensor positioning by keeping the desired shape during the complete process.

Depyrogenation

Depyrogenation tunnels offer limited gate headspace to optimize the sterilization process, making it difficult to introduce monitoring equipment. By using thermal barriers of different sizes, it is possible to find the best fit for the application. When the depyrogenation of small ampoules is being performed in a tunnel, the flat-pack offers a compact solution that is easily introduced with the load.

Method

When creating the thermal profile for a dry heat sterilization process, the main tests performed are heat penetration and heat distribution. The former is concerned with the heat generation inside the vessel and its homogeneity and the latter is focused on the heat transmitting from the vessel to the product and its effectiveness. This is normally measured in terms of lethality. The worst-case scenario is a recommended perspective as an acceptance criterion.

Data collection
Independent of the technique used for depyrogenation, static or dynamic, it is important to record simultaneous temperature data from a relevant number of points. Creating and documenting sensor positions is an important part of the documentation for the process control. Using the Unit tool within the ValSuite software with the option of multiple pictures makes it possible to have a documented map of sensor placement that will facilitate repeatable and comparable studies.

Once the position of the sensors in the chamber or tunnel have been documented, it is necessary to observe sensor placement inside the product. Using semi-flex metal sensors makes it possible to accurately position the sensing element in the cold spot. It is important to take into account the kind of heat convection used in the vessel and the shape of the product for the correct assessment of the cold spot. ValSuite software facilitates the documentation of sensor placement in the cold spot by allowing users to include descriptive pictures per every channel used.

Data analysis

When all data is collected, the homogeneity, stability and heat generation of the vessel is observed in order to create a good assessment of the heat distribution during all the phases of the process. ValSuite software provides tools to analyze the performance of the vessel in all phases of the process. The use of time-markers helps generate graphical and analytical reference points in the data collected. Statistics such as min., max., delta and Lethality FH (Tref =160°C, Z =20°C) are also available in the software. ValSuite integrates all calculations into self-generated reports without the need to export data into other software. Reports can also include logger placement inside the vessel and descriptive pictures of sensor positioning. Generating ValSuite reports provides the highest data security for the results due to the software being compliant with FDA 21 CFR Part 11.