Cleaning validation's troubles

Hi everybody,
I am involved in a new cleaning validation process for the replacement of the detergent used until now with the new cleaning agent Sodium Hydroxide.
To be more clear and to make you understand better our issue, I have to explain that the product that has to be removed from equipments is a protein.
Following you can find the flow of our cleaning activites:
a) Equipments have been cleaned with HPW to remove the main amount of protein residues (with a validated volume of water)
b) Equipments have been cleaned with Sodium Hydroxide 2-3%
c) Equipments have been cleaned with WFI to remove NaOH (final rinsing with a validated volume of water).

The issue is about TOC:
After phase a) we performed TOC to detect the amount of protein and the value was 300ppb.
After phase c) we performed TOC again and we found that the value was increased from 300ppb to 700 ppb.

Do you have an idea of the reason why TOC has increased? :confused:
Please let me know,
Thanks in advance.


Nobody can help me? :frowning: