Cleaning Validation-Swabbing Technique

I was looking for an ‘official’ description of the swabbing technique. Is the following wording adequate/correct?:

‘Each sample derives by swabbing 100cm2 equipment surface area for physicochemical analysis and 25 cm2 equipment surface area for microbiological control. The area is swabbed across in one direction, then the swab head is flipped and the surface is swabbed again at 90o angle.’

Many thanks,

Dear m.a
Whatever you have mention maximum majority of people are practicing or following the same even we also. As per my knowledge and experience I have concluded that there is impossible to freeze the limits for such type parameters. There must be a written, validated procedure having the sufficient data in order to prove the degree of improvement in cleaning etc.
R C Pantola

Dear m.a.,

in my opinion the wording is correct, but there may be more detail to the procedure. Our swabbing procedure states:

“Soak the swab in Y ml sampling solvent contained in a Schott tube and eliminate excess solvent by pressing the swab gently against the tube walls. Swab the area at least 10 times vertically and 10 times horizontally, holding the swab parallel to the surface, pressing the head of the swab against it with uniform pressure, and covering the surface entirely with the swabbed lanes. Swab the horizontal lanes with one side of the head of the swab and the vertical lanes with the other side, soaking and wringing out the swab in the solvent contained in the Schott tube in between the direction change. Finally, soak the swab in the solvent, wring it out thoroughly against the tube walls, and swab the surface diagonally to recover remaining solvent from the surface.With the swab in the tube, sonicate it for 30 minutes, transfer the solution to a graduated flask, rinse the Schott tube and the swab with X ml of fresh solvent, transfer the rinse to the flask, and adjust to the desired volume.”

Of course this depends from the type of swabs (ours have a flat head, 13 mm long and 8 mm wide), to cover the 100 cm² with 10 swab lanes and a reasonable overlap between them. In the end, the procedure depends from the target analyte, because for different analytes there may be different removal mechanisms (dissolution in the swabbing solvent, adsorption to the swab, mechanical removal, etc.), and which is prevailing is specific to the analyte.

Best regards



Does your analytical method validation report provide any information about how they swabbed the surface of the coupons used in the recovery studies? That’s where I’ve usually gone to get my swabbing instructions for my protocols, to ensure that the activities aligned.

Dear Mantonopoulou,

I think that if you insert some drawings of the direction of the swabbing (vertical, horizontal, etc) would also be very useful. We have also been asked to include in our procedures the number of times the swab is expected to be passed across the area to be sampled, so I think you should also include this information in your procedure.

Hello i am new to cleaning validation please help me to understand it ?