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Potassium Phosphate Buffer

Heinz-Juergen Schaefers h-j.schaefers at popHost.com
Thu Oct 31 13:39:20 EST 1996

Delvac Oceandy wrote:
> Dear everyone,
> Does somebody know the right content of Potassium Phosphate Buffer ?
> Is it a solution of Dipotassium hidrogen phosphate (K2HPO4), Potassium
> dihidrogen phosphate (KH2PO4), or Potassium phosphate tribasic (K3PO4) ?
> Or a mixture of those component ?


It depends on the pH you want to buffer...

Using KH2PO4 and K2HPO4 together in various ratios, you get an acidic buffer.
Using K2HPO4 and K3PO4 together in various ratios, you get a basic buffer.

the pH of the buffer depends on the ratio of the two components you use...
there must be a table somewhere in a common lab manual correlating the pH and 
the ratios... 
as a basic rule: if you take more of the component with more Hydrogen, you 
get a buffer with lower pH (more acidic).

Dipl. Biol. Heinz-Juergen Schaefers
University of Erlangen, Med. IV, Nephrology Research Lab
Loschgestr. 8, D-91054 Erlangen, Germany   +49 (0)9131 85-
E-mail: h-j.schaefers at popHost.com      -9206 (voice) -9202 (fax)

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