For what deviations are OOS investigations required: in-process test monitoring, excursions outside the historical range, environmental, critical quality impeaching, intermediate impurity tests (final impurity okay)?

As described in section 8.3, “out-of-specification (OOS) investigations are not normally needed
for in-process tests that are performed for the purpose of monitoring and/or adjusting the
process.” The in-process tests that you do where you are processing to a result are not normally
handled under OOS. For example, if you’re drying to a Karl Fischer of two percent and your first
result comes up at four percent, your batch record typically tells you, dry two more hours and take
another sample, or whatever the specific details are. That is an example of an in-process test to a
limit, and that would not need an OOS.