Justification for swab in cleaning validation


can anybody tell me which criteria we think during selection of parts for swabs in equipment


We select those locations which are worst case (where chances of residue present or not cleaned properly is more).

Dear Rahul,

we select our sampling points according to following criteria:

Possibility of being sampled: Obvious, but if a part cannot be sampled it should be dedicated.

Representativity: The sampling point should be representative or “worst case” of a bigger surface, e.g. in a vessel, the sampling point representative for the walls may be located, for insoluble analytes, in the upper part if the walls because contact time with detergents and rinse is shorter that in the lower part of the vessel. For soluble analytes (detergents) the sampling point may be located in the lower part of the vessel because the analyte is dragged with the rinsewater to the lower portion of the vessel.

Experience from the people who perform the cleaning and/or the people who inspect the cleaned equipment: This is probably the richest source to set the sampling points, because the people who perform the cleaning and inspection know exactly where they have to scrub more, or where to look, after an automated cleaning.

Accessibility/cleanability: The parts of the equipment not readily accesible for cleaning and inspection are of a higher contamination risk from the cleaning standpoint. Usual case for this category are wire mesh parts (extremely hard to clean because the contamination hides between the wires and only shows up when sampled by rinsing with an appropriate solvent) in fluid bed driers, fitzmills and sieves.

There is no priorization for these criteria, but if a sampling point responds to more than one of them it is clearly of a higher criticality than one that is selected only by one criterion.

Best regards



Thanks for detailed reply. But can we consider the different MOC of the parts for selection of swabs.


Hello Rahul.
We can offcourse consider different parts of vessels having different MOC.
Consider a vessel having sightglass (borosilicate), vessel walls (SS 316L). We can take sightglass and any location in the vessel (which are difficult to clean) for swabbing.
The swab recovery factor to be demostrated to all the different MOC by studying the swabbing recovery on coupons before start of the cleaning validation.