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Re: New column bad results
Posted: Sat Jun 08, 2013 12:00 am
by Andy Alpert
Mix equal molar quantities of H3PO4 and NaH2PO4. This will give a pH around 3.1. Then, add NaOH solution dropwise until you get to pH 3.5.
Re: New column bad results
Posted: Sat Jun 08, 2013 6:18 am
by danko
Phosphate wouldn't be feasable at pH 3.5 (pKa1 phosphate = ca. 2.2)
In that case acetate would be my suggestion.
Best Regards
Re: New column bad results
Posted: Sat Jun 08, 2013 3:26 pm
by Andy Alpert
Right; I meant 2.1, not 3.1. As for buffering at 3.5, formate's pKa is 3.7 while acetate's is 4.7. It would probably be better to start with unbuffered formic acid in water and add NaOH or NH4OH until you get to pH 3.5.