Visual Inspection: Visual Inspection is the examination of the dried equipment under suitable lighting conditions by personnel with appropriate standards of vision. Generally, it is used when it has been demonstrated that a calculated MACO would leave a visible residue as it is not intuitive that a validated method of cleaning would result in product residues.
Total Organic Carbon (TOC): Total Organic Carbon analysis is a non-specific method, looking merely for residual carbon molecules. The source of the carbon is not determined which arguably means the system detects potential residue from numerous sources such as the active ingredients, detergent, and in the biotechnology industry, cell debris and cell culture media. TOC is not applicable when the final rinsing solvent is organic.
The cleanest material available to the pharmaceutical industry is Water for Injection in Bulk (WFI) which has a TOC limit of 500ppb.
That any rinse samples or swabs would have a TOC result which is <500ppb. This means that the samples are within the range of WFI.
That any rinse samples or swabs would have a TOC result of <100ppb (for example) above a blank of the WFI in use. This latter limit is used to take into account that the WFI in use may have an insignificant TOC level (e.g.50ppb) and that there would be a potentially higher amount of carry over (e.g.400ppb) which would still meet the former specification.
HPLC and UPLC: they are the choice for cleaning validation where the active ingredient is well characterized (e.g. API). There are standard guidelines available for the validation of HPLC (ICH guideline Q2 (R1). Particular attention should be paid to the validation of limits of detection and quantification.
Conductivity: It is a non-specific method that has been applied to the analysis of inorganic molecules which result in ionic species when dissolved in water. This method is not generally used for the analysis of samples (swab or rinse) but conductivity can be found in parts washers where the cycle is terminated when a certain conductivity is reached.
Maximum Safe Carry Over (MSC)
It is calculated quantity of residue from the previous product (A) when carried over into the next product (B) that can cause potential harm to the patient. (It is based on the carryover for the batch)
It can be calculated as a limit to be applied to a result obtained when analyzing a sample collected at a specific point on the equipment train.
Any result exceeding the MSC is considered out of specification.
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