Making of phosphate buffer

5 posts / 0 new
Last post
boolean's picture
Making of phosphate buffer

Dear All

During one of the HPLC studies I have encountered a problem. I should prepare a 50mM phosphate buffer (pH=3,2) consiting of Na2HPO4·12H2O and NaH2PO4·2H2O. However I am unable to find any calculator to make it. Additionally as far as I know this buffer have reasonable capacity between pH=6 and pH=8. 

Could you provide me with the input how to prepare such buffer

Best wishes

protoldo's picture
Hola, In my desk manuals, I

Hola, In my desk manuals, I have one of buffers preparations from one of the first volumes of Methods in Enzymology. In the case of sodium phosphate buffer 0.2M from the mix of the 0.2 M of the monobasic and 0.2 M of bibasic , the range is from 5.7 to 8. So,as you say you could prepare a solution of phosphate 3.2 mixing the monobasic with phosphoric acid, but it don´t have buffering capacity. Good Luck

Dr. Analytical
Dr. Analytical's picture
There are many sources on the

There are many sources on the internet for doing these calculations.  Or, find a textbook on analytical chemistry.

I like the Zirchrom buffer wizard.

You must register with the site but access is free.

Note:  if you want to use solids to make your buffer, check the "100% by weight option."

jackiemorris01's picture
Thanks you Dr Analytical,

Thanks you Dr Analytical,
i too have had trouble preparing buffers  for specific pH tests (this is not my area of speciality) and welcome teh link you suggested.

boolean's picture
Thanks for a reply. I'll try

Thanks for a reply. I'll try to do it using the link you provided.