Specialty Chemistry Forums > Biochemistry and Chemical Biology Forum
pH shift in a Buffer Confusion
dbranch:
I resently made a Tris-EDTA buffer that is displaying an increase in pH as heat is applied. 5°C-->7.8, 25°C-->8.0, 37°C-->8.3. WWWHHHYYYY? To the best of my understanding, increased heat should increase ionization resulting inan increase in[H+] and a decrease in pH.
Help please, TIO
Babcock_Hall:
By itself TrisH+ increases in pKa as the temperature decreases, and ΔpKa/ΔT is about -0.03 pH units per degree Celsius. I would consider the possibility of an error in standardizing the pH meter, but I am just guessing.
Mitch:
Right, this might be a pH meter issue. Do you observe the same issue with just water?
jeffmoonchop:
I heard tris is dodgy with regular pH meters and should use Calomel ones. Anyone know anything about that?
Babcock_Hall:
Buffers: The Basics (RJ Beyond) mentions that not all electrodes are compatible with Tris, but it does not supply more information than that.
Navigation
[0] Message Index
[#] Next page
Go to full version