pH hepes - ...will NaCl & CaCl2 change the pH of hepes? (Jun/07/2010 )

we currently don´t have a pH meter:

I bought HEPES solution, 1 M, pH 7.0-7.6!
if i add NaCl and CaCl2 to this Hepes buffer - will the pH change that much?

for my purpose i need to have a final pH around 7,4!!

thanks for recommendation

moljul on Jun 7 2010, 01:16 PM said:

With a pKa = 7,55 (20 °C) the buffer has a good buffering capacity therefore adding NaCl and CaCl₂ will have almost no effect on the pH.

at 1M, no.

But at concentration below 1mM then yes. You will have ion concentration effects.