Dr. Duncan Clark duncan at
Sat Dec 21 07:47:07 EST 1996

In article <32B9F11D.38AE at>, Rick Bright <rbright at> writes
>I have an idea, hopefully someone can confirm or reject.  I keep my
>working buffers refrigerated and set them out about 30 min before the
>extraction.  When I initially made them (pH specific at 7.6) they were
>at room temp.  However, if I don't let them warm to room temp before
>using, the pH is much lower (around 6.1).  This could have a serious
>impact on my extraction procedure, I think.  
>1) Does this sound like it could be the problem?

This could be the problem. Tris is notorious for pH shift with
temperature. Your shift however is a lot more than one would expect 25
to 4C and the wrong direction for Tris! If you pH at 7.6 at say 25C then
the pH should go up as you lower to 4C ie approx 8.2. The other
components, in particular the EDTA may have something to do with this.  

>2) Do I need to keep the working buffers refrigerated?

No. Autoclave your buffer and store at room temperature in sensibly
sized working aliquots for your needs. 

>3) Do the buffers go bad after a period, say 30 days or so?

Shouldn't do.

I would remake your buffers.


The problem with being on the cutting edge is that you occasionally get 
sliced from time to time....

Dr. Duncan Clark
DNAmp Ltd.
TEl/FAX 01252376288

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