Ethylene Oxide (ETO) sterilization is mainly used to sterilize medical and pharmaceutical products that cannot support conventional high temperature steam sterilization – such as devices that incorporate electronic components, plastic packaging or plastic containers. ETO gas infiltrates packages as well as products themselves to kill micro organisms that are left during production or packaging processes. This gas, mixed with air at a ratio of at least 3% ETO gas, forms an explosive mixture. Pure ETO gas boiling point is 10.73 ºC at atmospheric pressure. Most of the time, it is mixed with Nitrogen or CO2.
Ethylene Oxide (ETO) sterilization ProcessMost ETO sterilization lines involve three different stages. These can be separated into three different cells depending on the size or amount of devices to treat:
- Pre Conditioning
Pre Conditioning StageFirst, products need to go through a pre conditioning phase to make micro organisms grow. The batch load goes through a dwell time under a controlled environment of : Temperature/Humidity
Sterilizer StageThen the load goes through a long and complex sterilization cycle. Requirements of such a system are :
- Accurate temperature control.
- Availability of the control system.
- Accurate pressure and vacuum control.
- Easy displays of process phases
- Dedicated customer recipes.
- Auto batching release through tolerance tests.
- Security interlocks between actuators.
- Shut down strategies.
- Audit Trail facilities – Trending.
- 21CFR Part11
Once the cycle is started, easy to use displays are required to show
- The actual phase of sterilization
- All the key set points and tolerances as loaded by the recipe
- All the key process values for the auto batch release facility
- Cycle start delay to enable the system to start in stable conditions
- General cell temperature check
- Initial vacuum phase
- Leak rate test
- First flush
- Second flush
- DEC (Dynamic Environmental Conditioning)
- ETO gas injection
- Sterilization dwell time period under ETO Sterilizer
- Post dwell vacuum level
- First wash
- Second wash
- Final air admission
- Final chamber re-evacuation delay
Batch logged files could be searched by the following
- Batch ID
- Customer name
- Product type
- Start and stop time