Rf: Re:fresh APS (former SDS-PAGE)

LOGAND logand at msdos.ensam.inra.fr
Thu Nov 30 04:51:32 EST 1995


Nikolia wrote:
> : Poor (slow) polimerization of acrylamide means that your APS is dead.
> : If the APS is freshly made and problem persists - dead TEMED
> : (instead to adding more TEMED buy new).

Paul N Hengen sent a tip:
> To test if the APS is too old, put some in a test tube and add the correct
> volume of H20 to make 10 mg/ml. If you hear it snap, crackle, and pop, then
> it is still good. At one time I looked into why it does this and all I could
> figure is that some gas forms (I forget if it is hydrogen or
oxygen?...somebody
> please tell me which) within the crystals when water is added to APS which
> causes them to pop. It is mentioned in Maniatis, but not explained why this
> happens.
>

Nikolia wrote again:
 
>I suggest for those of us who a litle bit odd of this "hubble-bubble sciense" 
>of
>testing APS :-), something more scientific.
>Prepare solution of NaI in water and add your APS to it. If the color changes 
to
>brown your APS is good. The reaction could be calibrated. The saturation of
>colorization depends from NaI concentration, and the rate of colorization
>depends
>from "how good the APS is".
>Nikolai
>http://128.252.119.253




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