Hoefer SE640 - Manual (Page 33)

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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, 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 Gel Seal 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
polymerization Allow acrylamide gels to set for a minimum of 1 h.
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 persulfate 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 mono-
mer 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.