Volatile buffers for lyophilization

larson eric elarson at ux1.cso.uiuc.edu
Wed Sep 28 08:05:15 EST 1994

at332 at FreeNet.Carleton.CA (Matt Parker) writes:

>	We are currently using 20 mM ammonium bicarbonate as the
>last buffer before lyophilization in our protein prep. Does anybody
>have any suggestions for better buffers? We are having a hard time
>getting all of the salt to evaporate.
You can try ammonium acetate, but you do lose some buffering capabilities
around the neutral range.
If you pull a vacuum on the samples prior to freezing, the ammonium
bicarbonate should drop.
If it were me?  I'd try exchanging into a lowered buffer concentration (1
to 5 mM) using dialysis, size-exclusion chromatography, or by
size-retention membrane concentration (Centricon or Centriprep devices).
If I might ask, why do you want to remove all of the buffer?
Eric Larson                  | University of Illinois at Urbana-Champaign
USDA/Agronomy                | 190 PABL; 1201 W. Gregory; Urbana, IL 61801
elarson at ux1.cso.uiuc.edu     | Voice 217.244.3079  Fax 217.244.4419
Fidonet: 1:233/4.1           | My opinions are my own, but correct :-) 

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