How to validate cleaning process if swapping is impossible

We are in a struggle with auditors as they doubt of a certain cleaning process.
The equipment involved does not have straight forward 10x10 cm² surfaces for swabbing.
More important is that you can not properly swap the system as it is too narrow to correctly manoeuvre with the swab.

In the past one could say that during final rinse you rinse till you get the same parameters as of your rinse water. Alas this is not accepted anymore.

If you have been in such a situation I will be very thankful if you’ld share your experience.




What type of equipment are you talking about? It could help to give an idea…

I think the main problema is that you are testing the rinse water lookking for some contaminats and I think that you have to follow the cleaning procedure and once the equipment is clean, you have to rinse with a known volume and test that rinse water… How dou you test the wáter? With an online system? Do you get the same data, ie, if TOC of wáter is 40ppb the TOC in your sample is arround 40ppb too?

I hope it hepls you,

Have a nice day!

It is a fiolling line. So needles. We have 3 filling lines.
Two lines run products that are clean when only rinsed with water (so washing without detergent) the other line is for more viscous products like coughing syrups).
Only the header can be swabbed and then it is not an easy area to swab.
Tubings and syringes are absolutely not swab-able.

So currently we do TOC but TOC does not indicate a molecule, just a ‘general cleanliness’.
We are looking towards HPLC, but seems that there are some problems optimising the method (water solubility and such).

so we are a bit t a loss how to approach. All advice is welcome.



Dear Johan,
You can choose rinsing or direct extraction as the sampling technique when you are unable to collect swab samples. First identify the solvent in which your product is freely soluble. Conduct the recovery studies using the same solvent and calculate the recovery factor. Correct the cleaning validation results with recovery factor.

Mr. Johan,

One way is to dedicate the syringes and tubing if you are not capable to take sample. other way is take a rinse from these and analyse. you need to have recovery study before doing this. apply MACO formula for rinse and calculate

Hi Johan,
Have you considered just pulling through the system a ball or wad of cotton?
You need to do recovery studies on a "mock up’ of the system - I assume that the area in question is a pipe/ tube?
If it is a tube/pipe then a similar diameter pipe can be “dirtied” with a standard protein or even your target product molecule of know concentration and volume, then dried.
Then you can see how much you can recover by pulling a ball or wad of cotton through the pipe.
Obviously you would have to standardize how you fold the wad or ball of cotton i.e. by an SOP.

hope this is of use


For small equipment surface area, you have a choice to use a smaller test area for swab samplings. You can have more swab samples but need not have to stick to 10 by 10 cm2. Just back prorate the surface area for the swab sample, not forgetting to use the same choosen surface area during swab recovery studies.