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fresh APS (former SDS-PAGE)

Paul N Hengen pnh at cockleberry.ncifcrf.gov
Mon Dec 4 13:05:53 EST 1995


RUTH MCMAHON (RMCMAHON at ollamh.ucd.ie) wrote:

| If I can add something here. I know that every source says to use fresh
| APS, but......I make 10% APS and freeze single use aliquots at -20 and it
| works forever! Well I haven't tested the forever part but it works for at
| least 6 months. Try it.
| 
| Jim Voeller

> Jim, you've been lucky.  When I was a grad student I tried doing the same
> thing you describe.  After a run of failed gels just when I was trying to
> finish off a paper, I traced the problem back to the APS.  I make it fresh
> every time now and teach my students and postdocs to do the same.  After
> all, how hard is it to make a 10% APS solution?  Dump some APS out an a
> weigh paper, see what it weighs, add enough water to make 10% and mix. 
> Takes about as long as defrosting a tube of frozen APS.
> 
> SRLasky

: Just to support Jim, I make up a 20% solution of APS and store it in 
: the fridge. I have never had a problem with any of my gels.
:
: Ruth. 

Well, I'm going to support Stephen on this one. It would take me longer to find
the bottle in the fridge or thaw the frozen tube than it would for me to tare
an eppendorf on the top loader and snap in a microspatula full of solid APS at
40-50 mg. As a habit, I can do this by looking at the amount of APS on the
spatula. But, maybe I'm different than most cause I can stick my hand in a
waterbath and adjust it to 42 C +/- 0.5 C without a thermometer :-) It also
keeps the students amused. No one in our lab will bet against me anymore ;-)

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* Paul N. Hengen, Ph.D.                           /--------------------------/*
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