WEF Discussion Forums : Laboratory Management and Technical Issues : BOD pH adjustment This may have been addressed before but we just recently bought SM 21st Edition and I was taking a look at the BOD method.

 

It says "Check pH; if it is not between 6.0 and 8.0 [adjust temperature], then adjust pH to 7.0 to 7.2..."

 

So, if I recieve a sample and the pH is 6.2 it's ok. But if the pH is 5.5 and I have to adjust it, then 6.8 is NOT ok. Really?? Can someone please explain this to me?

 

Couldn't they just leave it at "Neutralize sample to pH 6.5 to 7.5"?

 

 


]]> Thu, 27 Sep 2012 14:00:37 GMT The 18th edition says "adjust pH to 6.5 - 7.5" so somewhere between this and the 21st a change was made.

 

I am mystified as you.  I would have assumed that the final pH of 7.0 - 7.2 is to make sure the phosphate buffer is not overwhelmed by the use of a strong acid or base, but if that is so then why allow samples to be has high as 8.0 or as low as 6.0.

 


]]> Mon, 29 Oct 2012 16:22:57 GMT