Checking volume of prepared tablet coating solution before its application

I am a production pharmacist.

My question is:
For a certain validated tablet coating process in which the preparation procedure of coating solution and the quantities and specifications of chemicals used for preparation of coating solution are specified and validated , is it required that the volume of coating solution (after its preparation and before its application) is checked (to ensure that it falls within specified volume range) every time the coating solution is prepared during routine production of tablets batches?
Please if there is certain reference or guideline that mentions this issue please guide me to it.

Thanks a lot.

Yes, provided the volume of the liquid has been identified as a CPP (critical process parameter) in the validation study. I have no idea why it was not identified as a CPP for spray drying. What type of equipment are you using?

Fully Perforated Coating Pan Technology

Then yes! Both the composition and volume (relative to the lot size) should be identified as a CPP. I doubt there is a whole lot of automation with a pan.

But for me it does not make sense to ask tablet coating production staff to check the final volume of solution after its preparation that it falls within specified volume range although the quantities of each chemical composing the solution have already been defined and validated during development phase and each chemical quantity is double checked individually for every batch before solution preparation ??

Just have a checkmark in the ‘master batch record’ for that lot. It makes NO sense to identify it as a CPP but not monitor or document it!

So the final solution volume should be defined during development and validation phase only , then not routinely checked during routine production of tablet batches ??

No. You can have some lab mixes made and have a ‘hand held refractometer’ (they use them in wine stores) document the DS (dry substance) in the batch records. Be sure to have an acceptable range with a tolerance of the DS.

What is the relation between solution volume and refractometer ???
Unfortunately I do not understand your reply and its relation to the question
But thanks for your attention

The answer depends on the sample matrix (I used it for HFCS). The AOAC has a table of refractometer values, % Sugar, % Ethanol, and % Dry Substance (used for alcohol mashes). In any case you will have to develop your own table, consisting of refractometer value, % dry substance…