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

[Dr Koen A.L. De Smet]

packard at kersur.net wrote:
> 
> >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
> >
> >
The reason why they cannot be used after long storage is because the 
pH is not stable. Maybe I am just lazy, but I keep these buffers at 
room temperature for several weeks and when I want to use them again, 
I simply adjust the pH. This seems to work.
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        Dr Koen A.L. De Smet
        Research Fellow
        Department of Medical Microbiology
        Imperial College Medical School at St Mary's
        Norfolk Place
        London W2 1PG
        Great Britain
                                     
        Tel: (+44)-(0)171-594 3946  
        Fax: (+44)-(0)171-262-6299   
        Email: k.desmet at sm.ic.ac.uk
	       http://www.sm.ic.ac.uk/medmicro/home.htm
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"If we knew what it was we were doing,
 it would not be called research, would it?".   --   A.Einstein
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