Corrective action
Error description
Centrifuge or filter sample before loading to remove particu-
lates.
Protein streaks verti-
cally
Dialyze or desalt the sample.
To increase or decrease the migration rate, adjust the voltage
or current by 25% to 50%.
Unusually slow (or
fast) run
Adjust the solutions:
•
Check recipes, gel concentrations, solutions, and dilutions.
(For instance, do not use Tris-HCl instead of Tris.)
•
If the required pH of a solution is exceeded, do not back-
titrate. Prepare a fresh buffer.
•
Dispose of older acrylamide solutions and use only stock
of the highest quality.
•
Only use freshly deionized urea.
Check gel preparation and polymerization.
Bands are skewed
or distorted
De-gas the stacking gel solution and avoid trapping air bub-
bles under the comb teeth.
Overlay the running gel with water-saturated n-butanol before
polymerization begins to avoid forming an uneven gel surface.
Check sample preparation.
Dialyze or desalt the sample.
Centrifuge or filter sample before loading to remove particu-
lates.
Near the buffer front:
Stained sample col-
lects
•
Protein is not sufficiently restricted by the resolving gel;
increase the % T.
Near the top of the gel when the buffer front has reached the
bottom:
•
The gel pore size is too small. Decrease the % T of the re-
solving gel.
•
The protein has precipitated. Heat the sample at a lower
temperature (70°C or less) for 1–2 minutes.
SE 250/260 Mighty Small II Operating Instructions 29281629 AA
45
7 Troubleshooting
