Re: Tris or Phosphate buffer?

From:"John C. Dennis"


Unless you have one of those tricksy antibodies that genuinely prefers
TRIS buffer to PBS, I would use PBS.  The pKa of Tris is, depending on
where you read, 8.1, 8.2, 8.3.  If we take the middle figure and hope for
the best, adjusting the pH of your TRIS buffer to 7.4 means you're
adjusting the pH almost out of the buffering range of TRIS.  If you use
PBS, you're almost at the pKa of the monobasic buffering range.  So at pH
7.4, your phosphate buffer is your best bet.

John Carroll Dennis
Anatomy, Physiology, and Pharmacology
109 Greene Hall
Auburn University, AL  36849

On Sun, 11 May 2003 wrote:

> Sigma is no longer making premade Trisma Buffer pH 7.4
> We have always used their product in making our solution for the NADH muscle
> stain.
> I've experimented with a Sodium Phosphate diabasic/monobasic solution and the
> results looked the same as a NADH muscle stained with a Trisma buffer
> component.
> Can anyone tell me what the difference between the two buffers are and what
> factors I need to consider, if any, in transitioning to making the sodium
> phosphate buffer to replace the Trisma buffer?
> Lastly, does anyone know of a different supplier of premadeTrisma buffers,
> other than Sigma or Fisher (since Fisher gets their tris buffer from Sigma?)
> Thanks,
> Deb King HT
> Sacramento, CA

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