Filtration of 70% IPA solution

I have some queries please clarify it.
We use Filtered Disinfectant for cleaning purpose in Pharmaceutical industry. My query is that Isopropyl Alcohol kills Microorganisms So what is the need to Filtered Isopropyl Alcohol.

Another one is we use 90mm Petriplates for settle plate Exposure Why wr only use 90mm Petriplates.What is the reason behind it.

And Why We use 0.45 Micron filter in water testing rather than 0.22 micron.
Please clarify all my queries as soon as you can

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IPA is only used as disinfectant only,that means it will kill only vegetative cells and not the spores,and other hard spore forming organisms.

So,if we filter IPA it will remove all the organisms and also remains barrier to avoid transfer/cross contamination.

In 90mm petri plate / petri dish we will take 30 ml of agar media for settle plate method,its surface is sufficient for settle of particles because we are seening only criticality of the environment / area but not the qualitative analysis. You can also refer in EU guidelines,USP116,and in PDA 13.


0.45 micron membrane filter can retain large numbers of microbial cell smaller than 0.45 micron because this filter have multilayer and pores of this filter are in zigzag position.They are ramification of channels.


very useful msg to this type of hints is to be develop technique knowledge.

USP chapter 1231 have reference that filter with rating 0.45 micron is generally considered preferable although cellular width of some bacteria in sample may be narrower than this.The efficiency of filtration process still allow retention of high percentage of these smaller filter have many cross linkage,charges present on filter.
Smaller rating filter may be used but variety of reason ability of retained call on filter develop into colonies may be compromised. So it’s recommendation to use 0.45 micron size filter during water and sterility our purpose is to analyse the organism present in sample.with the use of 0.22 Micron rating filter chances of killing of organism is more as smaller pore size of filter pressure that used during filtration and variety of reason organism retained on filter not develop into colonies.hence our purpose of detection of organism from sample not achieve with 0.22 micron filter hence usp recommended use 0.45 micron instead 0.22 micron on the basis of variety of studies.