Adjusting PH

[smartin]

Hi,

I would like to prepare a mobil phase with semicarbazide and KH2PO4.
Then, I have to ajust pH at 2,85. What substance I have to use to acidify and basify it?

Thank you!!!!

[danko]

H3PO4 <–> H2PO4- + H+ pKa = 2.3

Best Regards

[Markus Laeubli, Metrohm]

bringing Danko's equation into words (and more):

a 1:1 mixture of H3PO4 and H2PO4 has a pH of 2.3

In your case, I recommend to measure the pH of the eluent.

eluent pH < 2.85 --> adjust with K2HPO4

eluent pH > 2.85 --> adjust with H3PO4

[smartin]

Thanks a lot for your help!!!!!