GE SE 250 Mighty Small II Operating Instructions Manual page 46

7 Troubleshooting
Error description
Poor band resolu-
tion
Bromophenol blue
does not sharpen
into a concentrated
zone in the stacking
gel
46
Corrective action
Use only the highest quality reagents.
Conduct the separation at a lower current or voltage setting.
Dialyze or desalt the sample.
Reduce the sample volume or concentration.
Only use freshly deionized urea.
Improve dissociation of subunits by heating sample in SDS
sample buffer 1–2 minutes at 100°C.
Add more mercaptoethanol or dithiothreitol; check sample
treatment.
Only use gels that were recently prepared.
Check pH values of the separating and stacking gel solutions.
Do not back-titrate buffers.
Sample preparation:
Heat samples for no more than 1–2 minutes at 100°C.
•
Store on ice after heating.
Store sample on ice before it is denatured.
•
Add protease inhibitors if necessary to prevent proteolytic
•
degradation of sample.
Store samples to be frozen in aliquots to prevent repeated
•
freezing and thawing. (Store at -40% to -80%.)
Pour a taller stacking gel. (For best results, allow a stacking
gel height of 2.5 times the height of the sample in the well.)
Dispose of outdated acrylamide solutions and use only the
highest grade of acrylamide.
When preparing samples, avoid using solutions with a high
sodium or potassium concentration.
SE 250/260 Mighty Small II Operating Instructions 29281629 AA