Dear Michael,

You have raised a good point about pH of a test sample.  Instead of measuring the pH of a diluted test sample every time that it is tested, I would recommend the usage of Buffeted NaCl Peptone Solution with preservative neutralizers to negate the pH effects of a test sample in a plate count diluent.  I have had seen that a products pH between 4 to 6 and 7 to 9 have an adverse effect on the recovery of microorganisms in a microbial count procedure.

Regards,
Don

Donald J. English Microbiological Quality Consulting LLC
Florham Park, New Jersey 07932

Sent from my iPhone

> On Nov 19, 2019, at 11:07 AM, Michael Barton <[log in to unmask]> wrote:
> 
> Good morning all,
> 
> I was under the imprerssion that for the testing of non-sterile products that during suitability and in routine testing the pH of the product in diluent must be checked and verified to be between 6-8.
> 
> I have just been reading <61> and under 'Suitability of the Counting Method in the Presence of Product' - 'Preparation of the sample' there are 5 product type options and only pH check and adjustment is detailed for water-soluble products and nonfatty products insoluble in water.  There is no mention of pH check within the remaining three types.
> 
> My question is therefore;
> If i am tetsing a product 'Fluids or solids in aerosol form' (one of the other three product types) do i or dont i need to check the pH and have it in the range of 6-8 for suitability and routine?
> 
> Why do you only need to check the pH for the two it specifically mentions?
> 
> Thanks,
> Mike
> 
> 
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Science Advisory Board https://www.scienceboard.net/

Steris - http://www.sterislifesciences.com/

Charles River Laboratories - http://www.criver.com/

Veltek Associates, Inc - http://www.sterile.com

Microbiologics, Inc. - http://www.microbiologics.com

BD Industrial Media - http://www.bd.com/ds/

Boston Analytical http://www.bostonanalytical.com/

Associates of Cape Cod, Inc. - http://www.acciusa.com/


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The nature of this service is to provide a medium for communication.  The specific statements and endorsements of individuals participating in the discussions are not necessarily those of The Microbiology Network, Inc., the PMF, or the sponsors of the list.