GE PhastSystem User Manual page 87

Symptoms
PhastGel IEF media
Streaking
Diffuse bands
Uneven iso-pH lines
"Smiling" bands
Probable Cause
1. Particulates in the sample.
2. Poorly soluble protein that
precipitates when applied to the
gel.
3. The sample has dried and aggre-
gated in the applicators before
being applied to the gel. The
aggregates are left on the gel and
leak protein during the run.
4. Dirty sample applicators.
5. Sample overloading.
1. The fixing solution was too old.
2. The proteins in the gel were not
fixed soon enough after the
separation.
1. Uneven electrode contact with the
gels.
2. Dirty electrodes.
The buffer capacity of the sample is
too high.
Trouble Shooting Guide
Solution(s)
1. Centrifuge or filter samples.
2. Try applying the sample at a dif-
ferent point. Decrease the field
strength for sample application
e.g. 200 V and 2.5 mA, or even
less.
3. Load the samples just prior to the
sample application step (espe-
cially blood and serum samples),
4. We recommend that sample ap-
plicators be used only once.
5. Dilute the sample.
1. Recycle the fixing solution no
more than 3 to 4 times.
2. Bands wills tart to diffuse im-
mediately after the method is
stopped: fix the proteins in the gel
as soon as possible.
1. Before starting a run, press along
the electrodes to ensure good con-
tact with the gel.
2. Clean the electrodes after every
run with a moist, lint-free cloth.
After running sticky samples such
as blood, you should remove the
entire assembly for thorough
cleaning under running water or
as described under Dirty elec-
trodes, page 2. Se also page 42 in
the System Guide.
Dilute the sample or reduce the
volume applied.
3