How to conduct rinse method in cleaning validation


I intend to conduct cleaning validation for a 1000 litres liquid preparation tank. My problem is that the tank is 2.8m high which means I cannot take samples in its bottom using swab or contact plate method. Therefore, I need to use rinse method in this case.

My question is how do I carry out the rinse method? And what is the acceptance limit for cleaning agent and microbial residue in this case?

Thank you all for reading my topic.


Rinse sample in cleaning validation is based on the volume of the tank. Take a trial and extrapolate it to different capacities in this case your tank.

Dear Kalyan

Pl. explain with an example of following sentance.
Take a trial and extrapolate it to different capacities in this case your tank.

Take a spiked sample and rinse with known quantity of diluent on known surface area. Check the content in diluent. Considering the recovery on NLT 80% increase quantity to ensure that there is no impact of increase in solvent. Fix the volume and Based on this calculate the quantity required for to be rinsed surface area

This topic is not much easy but there is no other way than this. Any other thoughts appreciated

Hi Kalyan,

Thank you for your answer. The core problem is here (in your answer): take a spiked sample and rinse with a known quantity of diluent on a known surface area. I can prepare a cleaning solution with a fixed volume, but how can we use the solution? I mean the question is how can we rinse a ‘known surface’? It is very hard because the tank is large as I mentioned.

Some companies in our country use the rinse method as follows: they collect water at the final stage of cleaning procedure. Then, they test the conductivity of the water. I don’t know what is the basis of this way.

Thanks again for the answer.

Taking rinse sample for evaluation and testing it for conductivity will not give appropriate results up to my knowledge considering the narrow limit. Once you rinse it is difficult to ascertain and being non-specific testing it would be inappropriate as you are not clear whether there is drug or not.
Further more what is the rinse sample solvent collected after cleaning?
What it’s your tank capacity

In this case TOC can be applicable.

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