Question

What is the most efficient way to make up a hepes buffer at 8.5? what starting compounds and reagents will you use?

Answer 1

The $pka$ value of HEPES is 7.5.

Now, to prepare a HEPES buffer at 8.5:

A proper amount of HEPES is mixed with distilled water (sterilised) to avoid any contamination. After that check the pH with the help of pH scale or pH meter.

Now, identify the pH and if pH is higher than 8.5, then a particular amount of hydrochloric acid is added to it drop by drop to get the HEPES buffer at 8.5.

If pH is lower than 8.5, then a specific amount of base such as sodium hydroxide is added to it drop by drop to get HEPES buffer at 8.5.

At last, when 8.5 pH is obtained, the buffer solution is filtered and placed in the container of the glass and then covered by aluminium foil.