Chemistry Reference
In-Depth Information
6.13 InvestIgAtIng oos test results
It should not be assumed that failing test results are attributable to laboratory error
without performing and documenting an investigation. If the OOS result cannot be
completely attributed to laboratory error, then a full-scale failure investigation must
be initiated, with the objective of identifying the source. Varying test results can
indicate problems in the manufacturing process, or result from sampling problems,
and therefore should be given the highest priority.
6.13.1 g
enerAl
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rIncIPleS
The failure investigation should be conducted by the quality control unit involving
all other departments that could be implicated. It should consist of a timely, thor-
ough, and well-documented review, and follow these general steps:
1. Clearly identify the reason for the investigation.
2. Summarize the manufacturing process sequences that may have caused the
problem.
3. Provide the results of the documentation review with the assignment of
actual or probable cause.
4. Determine if the problem has occurred previously.
5. Describe any corrective actions taken.
6. Include a list of other batches and products possibly affected and any
required corrective actions, and comments and signatures of appropriate
personnel.
6.13.2 l
AborAtory
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hASe
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nveStIgAtIon
During an OOS laboratory investigation, there are three possible outcomes:
• The suspect result is determined to in fact be accurate (or correct) and is no
longer suspect.
• The suspect result is determined to be inaccurate (or incorrect) due to an
assignable cause.
• The suspect results are determined to be inaccurate (or incorrect) and no
assignable cause can be established.
In the latter case, a retest may provide sufficient justification to invalidate or to con-
firm the OOS. During the laboratory investigation, these outcomes can give rise to
three possible scenarios: there is an assignable cause, a retest invalidates the result,
or no assignable cause is found and the result is confirmed. Figure 6.4 illustrates
an example result investigation summary that might be used during the laboratory
investigation. A written outcome, along with any documentation generated during
the course of the investigation (e.g., chromatograms, spectra, calculations, observa-
tions), should be included with the summary form.
