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

Joe Boutell boutell at cf.ac.uk
Wed Mar 26 06:57:20 EST 1997


"Dr Koen A.L. De Smet" <k.desmet at ic.ac.uk> wrote:
>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.
>_______________________________________________________________
>
>        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
>_______________________________________________________________
>
>"If we knew what it was we were doing,
> it would not be called research, would it?".   --   A.Einstein
>_______________________________________________________________

Yeah, I agree with this. The pH changes due to the dissociation of urea, 
so I keep my buffers for weeks and just adjust the pH just before use.

Cheers,
Joe Boutell. 




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