Gel or blot has a blue background

Find solutions if the gel or blot has a blue background after electrophoresis.

After electrophoresis, the gel or blot has a blue background

Possible causes

Solution

Cathode dye (containing Coomassie G) may still be present.

Once the first dimension separation is almost complete, the cathode dye containing Coomassie blue G should be replaced by the cathode buffer without dye.

Further electrophoresis will remove most of the dye from the gel.