Equipment cleaning swab sampling

Strege, M.A., Stinger,T.L., Farrell, B.T., Lagu, A.L., Total organic carbon analysis of swab samples for the cleaning validation of bioprocess fermentation equipment. BioPharm April 1996. 

Check that the equipment was cleaned properly following previous processing and that acceptable cleanliness was indicated by rinse and/or swab sample results. Ensure that all cleaning agents (e.g., detergents) have been removed from surfaces of the equipment. 

Let s revisit the cleaning of the tank and obtain samples from many different locations and choose sampling locations that fairly represent the entire equipment rather than just the single worst-case location. Let s assume that we still have the same total limit of 100 mg and that we still have the same tank having a total surface area of 100,000 sq. in. We still have the 0.1-mg swab for the manway gasket, but we now will take additional representative samples from each of several locations. Again we will swab areas of 2 in. x 2 in., just as we did previously. The data obtained are presented in Table 7. 

Isolators should have sufficient service port penetrations to allow as much equipment to be placed outside of the isolator as possible. Traditionally control boxes, chillers, keypads, and printers were placed as close to the analytical instrumentation being used as possible. The amount of equipment in direct contact with the samples should be minimized. If equipment needs to be placed in the isolators, the only way to remove that equipment later is to prove that the equipment has been cleaned to acceptable levels by swab testing. Based on experience, this cleaning is difficult to accomplish and in many cases the equipment needs to be considered contaminated and discarded if there is a need to remove it from the isolators. 

Cleaning is validated through liquid solvent sample analyses (dry weight and chemical identification of residue) and swab characterization according to the classical technique. It is extremely important to consider the cleaning issue at the very beginning of any SCF equipment design. This in-... 

As part of the validation of the cleaning method, the cleaned surface is sampled for the presence of residues. Sampling should be made by an appropriate method, selected on the basis of factors such as equipment and solubility of residues. For example, representative swabbing of surfaces is often used, especially in areas that are hard to clean or where the residue is relatively insoluble. Analysis of rinse solutions for residues has also been shown to be of value where the residue is soluble or difficult to access for direct swabbing. Both methods are useful when there is a direct measurement of the residual substance. However, it is unacceptable to test rinse solutions (such as purified water) for conformance to the purity specifications for those solutions instead of testing directly for the presence of possible residues. 

The toxicity of the residual materials should be considered when determining the appropriate analytical method and the residual cleaning limits. The residue limits established for each piece of apparatus should be practical, achievable and verifiable. The manufacturer should be able to document with supporting data, that the residual level permitted is scientifically based. Another factor to consider is the possible nonuniformity of the residue. If residue is found, it may not be at the maximum detectable level due to the random sampling, such as taking a swab from a limited area on that piece of equipment... 

The cleaning validation protocol should describe the equipment to be cleaned, methods, materials, and extent of deaning, parameters to be monitored and controlled, and analytical methods. The protocol should also indicate the type of samples (rinse, swabs) to be obtained, and how they are collected, labeled, and transported to the analyzing laboratory. 

---