Simple Question... Volts/amps for running mini gels? - Which volts/amps are the best, mine do not work! (Jan/15/2007 )
Hi everyone,
Just a quick question, its very simple but driving me mad!
When i run SDS mini gels (laemmli) i use the biorad mini protean II. (by the way webscientific.co.uk do good replacement glass plates).
My supervisor told me its best to run 2 gels at 50 miliamp through the stack and then 70 ma through the resolving gel. When she showed me how to do this she also pressed the 'constant amp' button. i have re-checked with her that this is correct and have tried to run this several times over the last few months. However, when i try to put it up to 70ma, the constant button automatically switches to 'constant volts'.
also when it is running, if i press the amp/volt button, it comes up at 300V!
Have i been running all my gels at 300 V for the whole time?
And how can i run them at 50ma and 70ma, if this indeed is correct?
Thank you in advance for any help, everyine else in lab just seems to run at constant 200v.
hi
generators can do at constant amp or constant V
On the otherhand, when you try constant A and so the Voltage nneded to do is over the maximum of your generator, the generator switches automatically to the max voltage (300) till it can switch t constant current.
I think that 50mA is quite hard?...
I've heard : turn 80V and see what is the Amp (let say 25).
Switch of, and turn to 25mA continue
your supervisor said 50 mA for 2 gels.
Maybe you ran only one?
I use 25 mA per gel and it works fine (25 mA if I have one gel, 50 mA if I have two gels). the voltage should be around 90V, but I set it over so it will not be the limitating factor.
I usually let these gels run at 35 ma (for 2 Gels) through the stacking gel and at 55 mA for resolving gel. This works fine, they don't get to worm and resolve really well.
thanks for all your replies, but what about the constant button? do i press it to constant amp or constant volts? and if iuse one, do i need to set both volts and amps?
very sorry about this, but its still unclear!
(and i was definately running 2 gels!)
in my power supply (BioRad) I choose what I want to keep constant (V or mA) and don´t mind about the other 2 parameters. I usually run 2 minigels at 95 V and this is only thing I choose. I think you only can set one parameter, which can be volts or amp and gels can run with any of them. You´d have to try and decide if your gels go better by running them at a constant voltage or a constant amp.
Right..
I think i will just have a play around then... sounds like 70ma wont run on the generator at constant amps because it isnt strong enough, so it switches itself to 300V?
sigh. silly things can be so confusing.
Try to change for a bigger generator if you want to maintain 70mA continue.
Try to change for a bigger generator if you want to maintain 70mA continue.
Thanks fred, i think my supervisor must have been mistaken then, it runs so fast at this 300V the resolution really isnt very good. i will try running it lower, thanks again
I tend to work in Volts? (100V with 2 mini gels) I am just out of step with the rest of the world.