Sampling Cleaning Validation

In developing the sampling plan for a validation study, it makes scientific sense
to
incorporate an understanding of the acceptance criteria and the limitations of the
sampling method relative to the surface to be sampled.
The two methods of sampling generally employed are swab and / or rinse
sampling. (If neither or these methods is shown be a scientifically sound method
for testing in a specific instance then an alternative is to consider testing the next
product.)
The selection of either of these techniques must be consistent with sound
scientific judgment and must support the objective of the study, which is to
demonstrate that the amount of residual material in the equipment has been
reduced to acceptable levels.
Each method is described in brief below.
1. SWAB:
· Swab sampling does not cover the entire equipment surface area therefore
sites must be chosen with care. It is important that, as a minimum, the
swab sites represent worst case locations on the equipment and that the
result is then extrapolated to account for the total product contact surface
area. This calculation makes it possible to make a worst case determination
of potential carryover into subsequent product.
· Due to the nature of this method which employs physical forces as well as
chemical forces it may be necessary to perform sampling technique
evaluation.
· Swabbing efficiency (% recovery) for the swabbing method must be
determined.
· It is necessary to ensure that extractables of the swab do not interfere with
the sampling method.
· Using this technique it is possible to sample insoluble residues due to the
physical action associated it.
2. RINSE:
· The solvent rinse occurs after cleaning has been completed
· This method is not as direct as swabbing but will cover the entire surface
area (and parts inaccessible to swabs)
· It is important to ensure chosen solvent has appropriate recovery for
residues being quantified
· This method allows much greater ease of sampling than swabbing
· A reduced no of samples are required to generate a carryover figure.
(Other sampling methods which may be employed in addition to swab / rinse
sampling during a validation may include: placebo sampling, testing subsequent
batches for residues, use of coupons (test pieces), etc. )