OQ (Operational Qualification) of a Freeze Dryer



Hi all,

I have a question regarding an OQ of a freeze dryer. Im Validation Manager in a medium size medical devices company and have the task to create a qualification plan for a freeze dryer (IQ/OQ/PQ) and encountered a problem while writing the OQ-plan. I have to say, I was never involved in any freeze drying process/qualification/ etc.

Maybe you guys can give me some advice..

The condenser capacity shall be tested. My idea of testing the condenser capacity was the following:

Stated capacity by manufacturer is 3kg

-make 2000mL of a 5% mannitol solution
-split the solution in 5 different glas beakers
-freeze dry the mannitol solution
-do a karl fisher titration to determine the residual moisture

-repeat the same process with the same volume of 5% mannitol solution but use 10 glas beakers a 200mL instead of 5 a 400mL

-Calculate the mean residual moisture for all dried product mentioned above.

Now to test capacity

for safety reasons (to not do any damage to the vacuum pump) I wouldnt test the absolute upper limit which is 3kg but 2.7kg instead (10% safety gap)


-make 2400mL 5% mannitol solution (i choose 2400mL because this volume will lead to 2.7 kg ice)
-split the 2400mL in 6 glas baeakers a 400mL
- freeze dry mannitol solution
-do a karl fisher titration to determine the residual moisture

-Compare the results of this tests to the results before. Residual moisture should be the same as with the 2000mL tests if condensor capacity is really 3kg resp. 2.7kg.

What do you think about the test procedure so far ?

Next question is:

How can I test the condenser capacity if there is NO possibility to determine residual moisture ? Any ideas ?

I really hope you guys can help me on that topic, as I think that there a many very qualified people in this forum.

Thanks a lot

Best Regards,



Involved In Discussions
Hi Ben

usually when i tested Freeze dryers, to test this i use to put a quatity of destilated water in shelf or recipients and run a cycle, after that i weigth the restant water and i could show how many water can be condensated by the equipment, i hope it help you.

Sergio ?vila


Ben, were you able to conclude this OQ plan. i am in same need. could please help me out in developing the approach of checking the capacity of freeze dryer?
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