Only when the method is precisely the same as described on the Certificate can you compare the results with de property value on the Certificate of Analysis. Another technique, media, or incubation temperature, can give other effects and can provide another result.
Checklist for root cause analyses:
1. Media – the most common cause of differences
Check if the used media and possibly used filters are fit your purpose. Therefore, performance testing of culture media according to ISO 11133 and performance testing of membrane filters according to ISO 7704 can be performed.
Search on the BiosistoStandard which kind of controls must be used as a minimum.
Check the incubation temperature and time if they are correct.
3. Used equipment
Check if the used equipment is fit for the purpose. For example, is the pipette calibrated.
How often does this problem occur? Is this structural or is it an incident issue?
5. Comparison with other labs
How do your results compare with other laboratories? An easy way to compare your results with other laboratories is to use the BiosistoChart. Ask for a free account for the basic functions
If you cannot find a cause for the deviating CRM value as a result of the above questions, please do not hesitate to contact Biosisto.