Visual inspection in cleaning validation

I would like to find out what is, more or less, the protein concentration that can be visually detected on a SS surface?

Thank you

Hi Neta,

For that you need to perform Visual Inspection of the sample protein on the SS surface. Since there are various proteins with different physical and chemical properties which have different effect on the visual detection. Design an experiment for visual inspection with the range of smallest protein concentration (which is the lowest protein concentration of your validated analytical procedure/method range) to the protein concentration which covers your cleaning acceptance criteria for that sample. And then have multiple inspectors to perform the visual inspection and you would be able to find out the lowest protein concentration at which you can establish the visual detection limit. Feel free to contact with any further questions.


It all depends up on the sensitivity of the protien assay you select either Bradford method or Lowery method. You have to standardize various concentration by swabbing those samples and testing those samples.
In 2007 there was a paper published and it detected up to 0.3 microgram level.

Thank you very much for your help.