making a master mix for SDS-PAGE

engelbert_buxbaum4 at engelbert_buxbaum4 at
Wed Nov 8 01:36:16 EST 2000

In article <dd0a4d989b.d989bdd0a4 at>,
> I don't know for sure
> what would happen if SDS were added to the mix, but I imagine it might
> precipitate out at cold temps.  Thus tempting you to warm it up before
> pouring... ;-)
> Why not test it out?  Not really much to lose.

At the 0.1% pH 6.8/8.8 commonly used in SDS-PAGE SDS is soluble in the
cold. This would be different for acidic gels, however. As long as you
degass with ultrasound, the mix can be made with SDS. If you want to
degass with vacuum, you better add the SDS later, from a 10% stock
solution, as you'd get a mess otherwise (been there, done that).

My own procedure is slightly different, I have separate stock solutions
for buffer/SDS and acrylamide/bisacrylamide. That way I can use the most
appropriate acrylamide concentration for each problem, but still mix the
gels with a minimum of fuss. I add water to the solid acrylamide in the
manufacturers bottle, assuming that the amount in the bottle is as
stated on the label (I just want to minimize handling of that stuff).
Then I add the bis and freeze the solution in aliquots.

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