The effectiveness of the preservatives used to keep the samples microbiologically stable during the period from the time the original packaging is opened until their use by the end user must be tested.
With this test, in which the preservative effectiveness is examined (Antimicrobial effectiveness test), it is determined whether the product is protected with the preservatives used in the product until the recommended expiration date after the original packaging of the sample is opened.
If no other standard has been reported, the Challange Test according to USP43 NF38 <51 >and EP 9.8 <5.1.3> standards is based on an artificial contamination created under laboratory conditions on samples and numerical data obtained from this contamination.
The result of the test is determined by logarithmically evaluating the number of microorganisms in the artificially contaminated sample at the requested time intervals (such as 0th hour, 6th hour, 24th hour, 2nd day, 7th day, 14th day and 28th day) according to the type of sample.
The process is initiated by inoculating the sample with the microorganisms Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Candida albicans and Aspergillus brasiliensis (Aspergillus niger) and a number of microorganisms appropriate to reference methods under laboratory conditions.
- Pseudomonas aeruginosa ATCC®9027
- Staphylococcus aureus ATCC®6538
- Escherichia coli ATCC®8739
- Candida albicans ATCC®10231
- Aspergillus brasiliensis (A. niger) ATCC®16404