Bio-Rad Sequi-Gen GT Sequencing Cell - Manual (Page 28)

3. Total Signal Artifacts
Condition Probable Causes Solutions/Preventions
Large horizontal exposed areas
of film
High molecular weight area
distorted on film
Fuzzy bands, bands smeared,
resolution problems
Autoradiogram shows large
black spots or radiating
patterns
Film sticks to dried gel
Blank autoradiogram
• Buffer contamination with
label
• Molarity or pH anomaly in gel
causing dehydration (gel
shrinking and bubbles) located
near the top of the gel
• Improper sample loading
• Hydrolyzed gel matrix
• Ionic contaminants in gel
• Polymerization problem
• Improper gel temperature
• Wet plastic wrap or wet gel
• Static electricity sparks
exposed film during handling
• Gel not completely dried
• Hygroscopic urea has bound
water
• Sample dependent problem
• Autoradiography problem
• Clean IPC and buffer containers,
remake buffers
• Gel run too hot, gel buffer
hydrolyzed, gel buffer not
made up correctly, or upper
buffer degraded
• Refer to Section 3.5
• Don’t run gel above 55 °C
• Use only electrophoresis grade
reagents, check purity
• TEMED or APS concentration
too high
• Pre-running gel may result in
better resolution
• Refer to Section 7.1 and 7.2
for protocols
• Refer to bulletin 1156
• Use Gel Temperature Indicator;
50 °C is usually high enough
• Re-expose with dry Saran
Wrap
• Do not rub film prior to placing
or removing film
• Dry gels longer. Remove urea
by soaking gel in methanol-
acetic acid before drying.
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