Bio-Rad Gel Doc™ EZ System - Manual (Page 36)

Criterion Stain Free TM System | Criterion Stain Free Gels
22
Electrophoresis Troubleshooting
Improper storage of Criterion gels can produce numerous artifacts. Criterion
gels should be stored flat at 4ºC.
Avoid freezing or prolonged storage above 4ºC. If you suspect your gels have
been stored improperly, DO NOT USE THEM.
Problem Possible Cause Solution
Samples do not migrate
into gel Tape at the bottom of the
cassette not removed Remove tape
Insufficient buffer in integral
buffer chamber Fill integral buffer chamber with 60 ml
running buffer
Insufficient lower electrode
buffer Fill both halves of the lower buffer tank with
400 ml running buffer when running two
gels
Electrical disconnection Check electrodes and connections
Bands “smile” across gel,
band pattern curves
upward at both sides of the
gel Excess heating of gel Check buffer composition
Completely fill both halves of the lower
buffer tank with 400 ml running buffer when
running two gels
Do not exceed recommended running
conditions
Skewed or distorted bands,
lateral band spreading Excess salt in samples Remove salts from sample by dialysis or
desalting column prior to sample
preparation
Insufficient sample buffer or
wrong formulation Check buffer composition and dilution
instructions
Vertical streaking Overloaded samples Dilute sample
Selectively remove predominant protein in
the sample
Sample precipitation Centrifuge samples to remove particulates
prior to sample loading
Gels run too fast, provide
poor resolution, and gel
temperature is too high Running buffer is too
concentrated Check buffer composition
Artifact bands at
60-70 kD Possible skin keratin
contamination Clean all dishware and wear gloves while
handling and loading gel
Filter all solutions through nitrocellulose
Use 10% iodoacetamide to eliminate keratin
bands