StarLab StarPhoresis N2510-1010 Manuel D'utilisation page 11

Problem: "SMILING" OF DYE FRONT
• The centre of the gel is running hotter than at the edges: use coolant or cold tap water in cooling
core and/or turn down current setting.
Problem: VERTICAL STREAKING
• Excessive sample or particles in the sample: either dilute sample or reduce voltage. Centrifuge
samples to remove particulate contamination.
• Sample has precipitated: Centrifuge sample before adding sample buffer or use a lower percentage
acrylamide gel.
Problem: BANDS SPREAD LATERALLY
• Diffusion of sample: Make sure the samples are loaded quickly and the power is applied as soon
as possible after loading.
• Diffusion of sample during the run in the stacking gel: Increase percentage of stacking gel or
increase current by 25% when stacking.
• Lower ionic strength of the sample: Match the ionic strength of the sample with that of the gel.
Problem: BANDS ARE NARROWER THAN THE SAMPLE WELLS
• Ionic strength of the sample is higher than that of the gel: De-salt the sample or use sample buffer
of the same strength as the gel.
Problem: DISTORTED SAMPLE WELLS
• Incomplete polymerization produces poorly defined wells: De-gas gel solution prior to casting and
increase APS and TEMED concentrations. he comb can be wiped with TEMED just prior to casting
to improve polymerisation.
• Salt concentration is too high in the sample: Dialyse sample or use desalting column.
Problem: RESOLVING GEL IS UNEVEN AT THE TOP
• Overlay gel carefully using water saturated n-butanol and make sure casting stand is level.
Problem: POORLY RESOLVED BANDS
• May be caused by too much sample for well width or gel thickness: Dilute sample.
Lower volumes generally give better resolution.
• Excessively high voltages cause fast run times, but poor resolution. Sample may have degraded.
Problem: FROWNING OF OUTSIDE LANES
• Leakage of Buffer along the sides or along the spacers inside the gel assembly: Do not move spacers
after polymerisation and make sure that the gasket is seated firmly against the glass.
Problem: DOUBLE BANDS – "DOUBLETS"
• Due to re-oxidation or insufficient reduction of the sample: If using a reducing agent, prepare fresh
sample buffer every 30 days. Increase the concentration of 2-mercaptoethanol or dithiothreitol in
the sample.
Problem: FEWER BANDS THAN EXPECTED WITH HEAVY BAND AT DYE FRONT
• Caused by more than one band migrating to the dye front: increase total monomer concentration (%T).
• Sample may have degraded due to incorrect storage and/or contamination.
StarPhoresis 2-Gel Mini and Wide Mini Vertical Electrophoresis Systems
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