Cleaning Validation Acceptance Criteria for Rinse Samples

For cleaning validation of liquid preparation tank (M/s. Airpac 2500/2000 ltr gross/working capacity); I planed to take rinse samples only since swabs will be difficult because of tank size.
What will be the acceptance criteria in this case?
I calculated the MACO (µg), then divided it by total contact area (µg/cm2), but after that I have to multiply it by the sample area, and here I could not decide what the sample area will be in case of rinse sample.

Is there another way of calculating the acceptance criteria in this case?

Thanks and regards

Points to consider Biotechnology Cleaning Validation.( this is a latest release just 2 months old)

  1. LeBlanc, D. A. 1998. Establishing scientifically justified acceptance criteria for cleaning validation of finished
    drug products. Pharmaceutical Technology 22 (1 0): 136-148.