Hoefer SE400 - Manual (Page 33)

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4. Troubleshooting
problem/possible cause remedy
Gel sandwich leaks while casting
Dirty or damaged components Plates, spacers, and the gasket must be completely clean.
Wash if necessary.
Replace chipped plates (especially if chipped near
the spacers).
Check the caster gasket for cuts or cracks and replace
if necessary.
Mis-aligned parts Check plate and spacer alignment and realign if necessary.
Over-clamping Turn cam only as far as necessary to create a seal (usually
90–150°, but up to 180°).
On each spacer apply a light film of GelSeal compound to the
bottom outside corner only. Do not use silicone grease.
Sample wells damaged or irregular
Air bubbles Remove air bubbles before inserting combs. Slide comb into
solution at an angle. If comb must be removed, add more
monomer solution before reinserting the comb.
Incomplete or delayed Allow acrylamide gels to set for a minimum of 1 h.
polymerization
Debris in wells Rinse out unpolymerized gel with sample buffer.
Comb removal Remove the comb at a slight angle and very slowly to prevent
damaging the gel.
Agarose gels: Lower the comb no more than 1 cm into the gel.
Incomplete gel polymerization
Chemicals Use only recent stocks of the highest-quality reagents.
If the dry ammonium persulphate does not crackle when
added to water, replace with fresh stock.
Increase TEMED or APS concentration, or both.
pH Solutions with extreme pH values (especially acidic) may
not polymerize.
Oxygen Remove oxygen from the gel environment: Degas the monomer
solution 5–10 min before pouring and then overlay the gel
surface with water-saturated n-butanol.
Temperature Adjust the gel solution temperature to a minimum of 20 °C,
especially for low %T gels.