We mentioned earlier that for an investigation to be meaningful it must be thorough, timely, unbiased, well-documented, and scientifically defensible. But what does this mean?
Let’s take a closer look at each of these attributes of a meaningful investigation.
1. Thorough
Investigations should consider all aspects associated with the event. For example if a dissolution apparatus was found to be stirring at an incorrect speed, the implications of this on all samples tested on that instrument since it was last calibrated should be considered.
2. Timely
Investigations should be completed in a timely manner and usually within thirty business days of being initiated. In addition, any corrective and preventative actions should be implemented within defined time lines.
3. Unbiased
Investigations should be carried out without any preconceived perceptions, for example a conclusion of ‘analyst error’ must only be reached if there is significant convincing evidence to support such a conclusion.
4. Well-Documented
All the findings of an investigation should be well documented, the use of appropriately designed forms can assist this.
5. Scientifically Defensible
Sound scientific principles should be applied to all investigations. A good scientific principle to apply is that of Occam’s razor which can be formulated as “hypothesis should not be made more complicated than necessary to explain the known facts”.
For example, if a HPLC analysis has yielded a low result, a failure to properly shake a volumetric flask should be ruled out as an explanation; prior to hypothesising “that because the HPLC vial was filled to the top, before being capped, a partial vacuum was formed, in the vial, when the sample was taken for injection into the HPLC, resulting in a reduced sample volume being taken”.