Hi All,
I want to make HEPES buffer solution and when I search for the composition I could find two different types of it. Can anyone help me which one is the correct method of HEPES preparation?
Following are the two sites which I referred,
http://protocol-place.com/basic-lab-techniques/stock-solutions/hepes-stock-solution-0-1-m-ph-7-4/
http://cshprotocols.cshlp.org/content/2010/7/pdb.rec12259.full
This site gave a completely different composition. All these ingredients are to be added ?
Hello Ada Zwetlana
the first link shows you the recipe for a classic Hepes buffer. This buffer consists exclusively of HEPES with the adjusted pH value by the NaOH pellets.
The second link shows you a HEPES buffer which is probably used for enzymatic determinations. So it is specially designed for a specific application. Depending on your experiments you can add different substances to your HEPES buffer.
So if you only need the buffer for buffering to keep the pH value constant or as a nutrient buffer, you can use the first link
For more specific applications, it depends on the method
I hope I could help you.
Hello Ada Zwetlana
the first link shows you the recipe for a classic Hepes buffer. This buffer consists exclusively of HEPES with the adjusted pH value by the NaOH pellets.
The second link shows you a HEPES buffer which is probably used for enzymatic determinations. So it is specially designed for a specific application. Depending on your experiments you can add different substances to your HEPES buffer.
So if you only need the buffer for buffering to keep the pH value constant or as a nutrient buffer, you can use the first link
For more specific applications, it depends on the method
I hope I could help you.
Oliver Handorf Thank you so much Dear Oliver. That was really helpful.
HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) is a zwitterionic sulfonic acid buffering agent, thus it has an acidic sulfonic acid group (pKa ~3) and a weakly basic piperazine group (pKa ~7.5). This means that HEPES could be purchased as a sodium salt (mw 260), or free acid (mw 238) (the sodium salt is 22 g/mole greater in mass because one hydrogen (mass 1.0) has been replaced by one sodium atom (mass 23)). Either the free acid or the sodium salt could be used to produce a buffer, however, the concentration of sodium ions will be greater in the buffer if you started with the sodium salt and pH'ed the solution with HCl, than if you start with the free acid and Ph'd the solution with NaOH.
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