Supporting process failure investigation

Once the retesting protocol is executed successfully (i.e., no analytical deviations), the results will either support the OOS result and confirm a material failure or render the OOS result invalid and provide ample justification to pass the test specifications. If the OOS result is confirmed, the batch is rejected and the quality assurance department should take appropriate steps for batch disposal. Since confirmation of the OOS result strongly suggests an operator-related or process-related error, the onus is now placed on the formal or phase II investigation participants to identify a cause. If an operator-related error is found and batch rework is possible and prescribed in an approved batch record and approved regulatory submission, this may be the desired course of action. If no rework or reprocessing is possible, the batch is rejected and disposed of in an acceptable manner. 

As mentioned before, ESR spectroscopy has been used extensively for the study of electrochemically generated radicals and radical ions 40 A word of caution is necessary with regard to the interpretation of such results the detection of a particular radical species is no definite proof that the radical is an intermediate in the formation of products. This can only be established by supporting the ESR studies by kinetic investigations. Also the failure to detect radicals from an electrode process does not mean that radicals are not intermediates, only that they may be too short-lived to be detectable. Generally, one can estimate the lower limit for detection of radicals from electrode reactions at a half-life of about 0.1 sec for external generation and 0.01 sec for internal generation. 

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