My protocol for making a 4 % PFA fixative solution recommends dissolving PFA in water and heating to 60'C while adding NaOH dropwise to help the powder go into solution. Multiple protocols that I've seen online have stated not to boil the solution or even to let the solution go above 65'C or especially 70'C.
I have not been able to find out why it is recommended to not heat above this temperature. does it polymerize? does it release formaldehyde gas? or formic acid?
The reason I ask is that a colleague has always made his 4% PFA by adding boiling water to premeasured powder. Given that he isn't measuring the temperature of the water when it is added, I told him this was not recommended, he asked me why and I couldn't give him a reason.
Do any chemists out there know the answer to this question?
Natalia Kuhn
Heating of the paraformaldehyde is not necessary, since depolymerization may take place at room temperature. We conclude that formaldehyde prepared from paraformaldehyde remains stable for considerable periods of time, and it is therefore unnecessary to prepare it immediately prior to fixation.
Article Formaldehyde prepared from paraformaldehyde is stable
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