sds page - hot hot hot - buffer too hot - gel burnt (Jan/31/2011 )

Hi everybody!
Today I saw a strange thing I have never seen before:
I ran a NuPage Novex 4-12% Bis-Tris Gel (Invitrogen) in 1x NuPage MOPS Buffer (diluted from 20x stock - 40 ml stock + 760 ml H2O) at 200V with constant voltage. When I returned to the gel after 30 minutes, the marker bands had migrated twice as far as usual, the buffer was boiling, the gel was cracking and the bottom of the gel had burnt!! Sample treatment and all conditions where the same as usual! Anaybody an idea what could be the reason for this overheating???
Hope you can help me!!!

Expired buffer? I don't know... my MES buffer works fine...
Did you check the amp?

It really sounds like your buffer is too concentrated, is it a new stock solution?

Are you sure the power supply was delivering constant voltage? If it was set for constant current, the voltage would go high as the resistance increased (or you set it for 200 mA). In any event, if your apparatus was assembled correctly, and your buffer was correct, I'd try a different power supply...

Yes, I opened a new buffer stock.
Voltage was set constant to 200V.
Power supply worked normally the day before and the day afterwards - how's that possible

Hanna30 on Tue Feb 1 08:16:12 2011 said:

Hmn... the day before is ok, the day after is ok, but not the day itself....
Are you sure you are adding the correct stuff that particular day? Or maybe someone was sabotage your work.... is time for a hidden CCTV...

is the hot gel from a different lot than the gels from the days before and after? it may have dried some, altered buffer, or be from a "bad" lot.

were the samples extra salty or in any way different from the samples you ran before?

(not to insult, but to troubleshoot) are you sure that you properly diluted the electrode buffer?