Why Does The pH of Nycodenz Decrease? - (Aug/13/2007 )

I would like to know if anyone has done a study of this reaction. Could the iodine change the pH over time?

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we also work with buffered Nycodenz gradients; I think we do not monitor the pH of buffered Nycodenz as we do not know the problem of changing pH...

what is precisely your observation?

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Added to the nycodenz (570mosm/L) is the water + tricine to get it to a 300mosm/L, then the 300mosm/L NaCl dilutant is added to get the desired density. This solution is stored in the 4C refrigerator. When needed, this solution is brought to room temp. and then opened and used. I have noticed this decrease in pH by 0.07 with all of my mixing solutions - - DPBS, NaCl and nycodenz having tricine in them and no NaCO3. Could the CO2 content of the solutions (water) in the opened containers be changing during temp. shifts from 4c to 25C?

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