Chemistry - What happens if you autoclave HEPES?

Solution 1:

From here:

Some buffers (e.g., MOPS and HEPES) cannot be autoclaved because they degrade upon heating.

and from here:

[HEPES] Solutions may be autoclaved under standard conditions.

I guess nobody knows the answer.

Solution 2:

Today I tested a set of competent E. coli cells that were prepared using a HEPES-based calcium chloride buffer solution. The solution was autoclaved as I described in the answer.

I obtained a fair transformation efficiency from these cells, and viability was also not perturbed noticeably. There are several confounds in the preparation of my solution that could affect the transformation efficiency, but in conclusion, autoclaving the HEPES has not abrogated its ability to make cells chemically competent.

I will speculate further and say that autoclaving HEPES may degrade some of the HEPES molecules or produce reactions and generate unexpected subspecies - but both of these will be generated in small, insignificant amounts which should not affect most biological applications.