Correct method for qualification of incubators used to incubate settle plates


I am new to validation and as such would appreciate advice on the correct way to place thermocouples in an incubator that will be used to incubate settle plates. Should I place the thermocouples within the agar plates and if so are there any issues that I may see during the thermometric mapping? If using agar plates will result in erroneous results is there another
representative method that I could use?


Hello Dr. Andrew,

You should normally place thermocouples or probes at various places with in your chamber and monitor both Teperature and Humidity.
For specific studies as in your case its advisable to stick the thermocouple to the top lid of the agar plate and close that.
In any way of inserting or placing thermocouple on the agar media is not adavisable. It will be a stedious job to clean such thermocouples after use.
If you have a robust cleaning SOP you can insert the thermocouple into agar media at specified locations max 6 plates.
This can be done as a secondary study. The primary would be monitoring the chamber temperature.


Thank you Durga, I will look at following your instructions. Am I right in thinking that the thermocouple positioned on the inner lid of the agar plate will be representative of the temperature on the surface of the agar?

Dr. Andrew,
If you place that thermocouple for atleast 2 to 3 hours and monitor the temperature regime it would suffice the need. There will be tranfer of temperature thru convection and conduction in such ovens. So placing a thermocouple on the upper lid of a petri dish or a plate would be a ideal representation of the system.
In microlabs if you place thermocouples inside agar plates and monitor cleaning such thermocouples will be come an issue.
If you use very sensitive micro cultures for recombinant productions I would reccomend you to place the thermocouple inside the solidified agar medium.
If you use normal cultures they are generally robust to such temperature fluctuations by 0.5 degree + or - .