RH Data Loggers in Ethylene Oxide Environments
Ethylene Oxide is a widely used sterilization process worldwide. It is a very effective sterilant, but it presents several challenges for the data loggers used to monitor and validate the cycles, not the least of which is the inherent sensor drift that can occur in electrical sensors from usage in Ethylene Oxide environments, particularly with RH (Relative Humidity) data loggers.
All RH data loggers are affected by Ethylene Oxide. In an independent study conducted 2 years ago, it was found that all the RH data loggers used in the study from several manufacturers were affected as soon as they were exposed to EO, some more than others. It has been determined that over time, particles can become embedded in the sensor substrate; this entrapment will cause the sensor calibration drift and this effect is cumulative over time.
With this in mind, there are a few steps one can take to minimize the impact that EO exposure has on RH data loggers:
1. Pre and Post exposure conditioning.
Mesa has developed a procedure to heat the RH data loggers after exposure to EO to accelerate the out gassing of the sensor and bring it back into calibration quicker. In addition, Mesa has EO customers that store their RH loggers in pre-conditioning rooms where they maintain conditions at about 100°F and about 80% RH. This has shown to be a successful way to store the loggers and maintain their calibrations over a longer period of time.
2. Use only as many RH data loggers as necessary.
As all humidity data loggers are impacted by Ethylene Oxide, the user should find a mix of temperature and RH loggers that gives the information necessary, yet limits the impact that EO can have on the data received from a particular cycle.
3. Utilize Manufacturer’s representatives
As this is an industry-wide issue, consultation with the manufacturer’s representative is crucial to determine what steps can be taken to preserve the validity of your validation process.
Mesa offers DataTrace data loggers that are intrinsically safe for use in EO and have been shown to minimize the effect that EO can have on RH readings if the proper steps are taken before and after the sterilization cycle.