Urea-containing buffers: How long can I store them?

David B. Flora Flora_David_B at lilly.com
Fri Mar 28 03:06:20 EST 1997

Viraj Master wrote:
> Hello all,
> I am using the Qiagen pQE series of vectors to express proteins.  There
> are two buffers which I use a lot, Buffer B and Buffer C.
> These contain:
> 8M urea
> 0.1M NaH2PO4
> 0.01M Tris
> Buffer B is at pH=8
> Buffer C is at pH=6.3
> I have been told that I must make these buffers up **fresh** each time
> prior to use.  I would like to be able to prepare batches of these
> buffers and store them.  Does anybody know whether this can be done and
> not affect the protein prep?  If so, are they stored in the cold, or at
> room temp?  For how long can they be stored?
> Many thanks,
> Viraj
> Viraj Master PhD
> Dept of Organismal Biology
> University of Chicago


I am a biochemist at Eli Lilly and Co. and we use 7M urea quite a bit
and make up 10L batches.  We store them in a cold room to reduce the
formation of a break-down product that results in the carbamylation of
primary amines in proteins we work with.  We also pass the urea through
a column of a mixed-bed ion exchange media (Amberlite).  The column
removes the urea break-down product and we see little carbamylation of

Dave Flora
Diabetes Research
Eli Lilly and Co.
<these are my opinions and not those of Eli Lilly...>

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