Distorted protein bands |
Air bubbles in the sample wells |
Use a syringe or a pipette to flush the sample wells
thoroughly with running buffer before sample loading |
Some part of the tracking dye changed to yellow
|
Buffer enters gel because of broken cassette |
Gel tank is not compatible or cassette was damaged |
Gel wells are not fully submerged with running buffer due to not enough
buffer
loading or cassette leakage |
-
Add more running buffer in the cathode tank cassette (between the two gels) until it
overflows from the gel wells;
-
Press the gel firmly into the cassette to ensure it is fully sealed;
-
Use a functional/not damaged thank cassette
|
Streaking |
Insoluble or weakly charged particles (such as carbohydrates) exist in the
sample |
Heat up the sample in the presence of SDS, centrifuge sample and load the
supernatant |
Electrophoresis time is too long |
Check the specifications of the power supply if it can
support multiple gel runs at the same time |
Peel the seal off from the bottom of cassette before
loading |
Incorrect running conditions |
Use fixed voltage and automated current, e.g. 140V throughout the
electrophoresis |
Electrophoresis does not start with error shown on the power
supply |
Seal is not removed from the bottom of the cassette
|
Peel the seal off from the bottom of cassette before
loading |
Bands are not well separated |
Incorrect gel percentage |
Use the protein migration table to choose the
appropriate
gel |
Sample overloading |
Reduce sample loading amount, especially when the sample contains many kinds
of protein. |
Insufficient SDS in loading buffer |
Increase SDS content during sample preparation |
Insufficient buffer to keep tank cool |
Add more buffers to the outer tank until it is at the same level or above
the
top of the sample wells |
Sample spreading across the gel |
Sample contains too much salt |
Reduce sample salt content by dialysis or
ultra-filtration |
The voltage cannot reach the set value |
Leaking between the inner and outer tank during run |
Use compatible gel tank |
Run too many gels on the same power supply |
Check the specifications of the power supply if it can support multiple gel
runs at the same time |
Lots of air bubbles between the gel and the cassette |
Overheat might be the cause, especially if running buffer is hot after
electrophoresis |
Add more running buffer to the outer tank |
Sample do not separate or migrate with a low current |
Gel wells are not fully submerged with running buffer due to not enough
buffer
loading or cassette leakage |
-
Add more running buffer in the cathode tank cassette (between the two gels) until it
overflows from the gel wells;
-
press the gel firmly into the cassette to ensure it is fully sealed;
-
use a functional/not damaged tank cassette
|
Wide and narrow bands in the gel |
Differences in conductivity of the sample might be the cause. If the
conductivity of the sample is high (more salt) the bands will become wide and if it is low
(less salt) will become narrower. |
Adding sample buffer to the blanks and ladder will help to equalize the
conductivity and migration. |