Overlapping Rinse and Swab Samples

Through my searches and training I have found that swab and rinse samples are acceptable to use in cleaning validation. I’ve run into a new practice that I have not seen before. I am wondering if there are any regulations or guidances on ovelapping samples. To be more specific, is it acceptable to rinse sample the entire product contact surface area of a tank, then swab sample the tank, and then add the results from the rinse to each swab collected? I’ve always heard this is not acceptable but I can not find any regulations or guidances against it. Please help me find a regulation regarding this. Thank you.

Dear RAE,

As per my knowledge and experience…

Choosing of a sampling method (in cleaning validation) depends on its recovery rate and complexity of the equipment. No need to take sample from entire equipment train using a unique sampling method. (for example, in injection filling line, I will use swab sampling method for compounding tank and rinsing method for filling machine). No guideline suggests the practice defined by you. If the recovery rate is less than 75% in unique sampling method and more than 75% in dual sampling method, then your practice may be supported. However, if you do the dual sampling in cleaning validation, you have to use the same practice for routine testing (of cleaning residues)