Can I prepare SDS-PAGE gel mixes in advance?

Steven Cohen sbc4 at PO.CWRU.EDU
Wed Jan 22 20:48:16 EST 1997

>Acrylamide is unstable and will break down, by deamination, to acrylic acid
>in a reaction catalysed by light and alkali. I'm not sure of the details,
>but by checking the pH of and old acrylamide solution will give an
>indication of whether it has broken down yet. Also adding a small amout of
>basic ion exchange resin will help preserve it. You should therefore not
>add the acylamide to your mix until ready to use it. The Tris, water and
>SDS can however be mixed in advance.
 While Acrylamide does break down this is a very slow process. There are
many vender who sell premixed Acryl and Acryl:Bis solutions. Better than
using pH to monitor the process, I would suggest conductivity. Most
commercial solutions are spec'ed at less than 10 micromhos for the
concentrate. (30-40%) There are even reagents that are complete mixtures
with SDS, TBE,ect. While I make these myself, I always prep enough for a
week or two and never have a problem or see changes in migration.


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