[Nand Morren]

Dear chem enthousiasts,

I'm working on a project that involves using a high concentration potassium citrate buffer of 1,5M at pH 4,9 (prepared from citric acid anhydrous and K3citrate)

Unfortunately, the solution is very susceptible to crystallisation. I was wondering what temperature can be applied in order to resolubilize the crystals. Where is the limit before I will start to decompose the material. Will the pH balance around the intermediate salts their pKa shift? What temperature should I maximally apply?

Furthermore, is there a way to determine the minimal temperature to guarantee in order to avoid cristallisation phenomena?

Best,
Nand

[Borek]

Heating up can help, citric acid melts without decomposition at 156°C, so even at boiling I would not expect any problems. pH will definitely change on heating, but should go back to the original value after cooling.

The only sure way of determining the minimum temperature is by experiment.

[jeffmoonchop]

Why do you need such a strong buffer? If you come down in concentration a bit, even 1M it would still be strong and you'd get less crystallization