Bio-Rad DCode™ Universal Mutation Detection System - Manual (Page 84)

Buffer temperature does not 1. Use 50% ethylene glycol as chiller
coolant.reach set temperature
2. Insure that DCode temperature
controller is set at desired buffer
temperature.
3. Check that chiller is set to –20°C.
Air bubbles in gel Clean glass plates
Fuzzy DNA bands 1. Clean wells before use. Check for
matching comb and spacer thickness.
2. Let gel polymerize for at least 60 minutes.
Bands did not migrate far 1. Increase run time.
enough into gel 2. Decrease acrylamide concentration.
3. Increase voltage or power.
DNA leaks between wells 1. Acrylamide not polymerized. Add
more TEMED and ammonium
persulfate to final concentration of 0.1%.
2. Degas acrylamide solution before casting
gel.
3. Let gel polymerize for at least 60 minutes.
4. Do not overload sample well. Reduce
sample volume.
Skewed or distorted bands, 1. Impurities in acrylamide. Filter before use.
or DNA spikes in gel Check shelf life date of acrylamide.
2. Carefully load DNA in wells. Do not
pierce or puncture wells.
PTT
“Smile effect”–band pattern curves Decrease power setting, or fill lower chamber
upward at both sides of gelwith buffer up
to the "Max" setting on tank
Air bubbles in gel Clean glass plates
Fuzzy DNA bands 1. Clean wells before use. Check for
matching comb thickness and spacer
thickness.
2. Let gel polymerize for at least 60 minutes.
Bands did not migrate far 1. Increase run time.
enough into gel 2. Decrease acrylamide concentration.
3. Running buffer too concentrated.
Check buffer protocol.
4. Increase voltage or power.
Skewed or distorted bands 1. Acrylamide not polymerized. Add
more TEMED and ammonium
persulfate to final concentration of 0.1%.
2. Degas acrylamide solution before
casting gel.
3. Let gel polymerize for at least 60 minutes.
80