# Gel voltages and times

Warren Gallin wgallin at gpu.srv.ualberta.ca
Fri Feb 9 11:51:26 EST 2001

```The important parameter is actually the voltage gradient, V/cm.  The
trick is, you have to measure the electrode-electrode distance, which is
not necessarily the length of the gel.  So, if you happen to be running
the two gels in the same submarine apparatus, you would not change the
voltage at all.  If you are using a smaller apparatus, the ratio of the
inter-electrode distances is the relevant factor.

Warren Gallin

"Paul S. Brookes." wrote:
>
> I have a real silly question about gel voltages.... Is the voltage you
> apply across them determined by the length, or the cross-sectional
> area?
>
>  The protocol I'm working from uses 120V, 12hrs,  for a 140 x 140 x
> 1.5mm gel - i.e. 210square mm  cross-sectional area, 140mm length.
> I have a 70 x 90 x 1.5mm mini-gel, i.e. 135 square mm area, 70mm
> length.
>
>  *  So, seeing as my gel's x-sectional area is 64% of the bigger one,
> do I use 64% of 120V = 77V
>  *  Or because the length is 50% do I use 50% of 120V = 60V
>  *  And how long to run for?  Does half the length = run for half the
> time?
>
> Is there a simple equation for working out voltages based on gel % and
> dimensions?
> Thanks in advence for any help.
> Paul
>
> _________________________________________
> Dr. Paul S. Brookes.            (brookes at uab.edu)
> UAB Department of Pathology,   G004 Volker Hall
> 1670 University Blvd., Birmingham AL 35294 USA
> Tel (001) 205 934 1915     Fax (001) 205 934 1775
> http://peir.path.uab.edu/brookes
>
> The quality of e-mails can go down as well as up

```