b'ElectrophoresisObservation Possible cause Suggested solutionRun taking longer time withRunning buffer too dilute Make fresh running buffer and use a 1X dilution.recommended voltageCurrent too high and excessive heat generatedRunning buffer too concentrated Make fresh running buffer and use a 1X dilution.with recommended voltageCurrent too low or no currentRemove the tape from the bottom of the gel cassette prior to with recommended voltage Incomplete circuit electrophoresis. Make sure the buffer covers sample wells; check the wire connections on the buffer core.Sample overload Load less protein.High salt concentration in sample Decrease the sample salt concentration by dialysis or gel filtration.Streaking of proteins Sample precipitates Increase the concentration of SDS in the sample.Contaminants such as lipids or DNACentrifuge or clarify the sample to remove particulate contaminants. complexes in sample Treat sample with nuclease(s).Poorly poured gel Make sure the gel is poured evenly and all at once.Protein sample only partially denatured Fully denature the protein. Fuzzy bands Protein sample only partially reduced Make sure a sufficient amount of DTT or -mercaptoethanol is added.Gel runs for too long Watch the dye front as an indicator for proper running time.Loading a large volume of sample causesLoad appropriate volume of sample. If the sample is too dilute, incomplete stacking concentrate it using ultrafiltration.Uneven electric field during run Try to make sure the loading is symmetrical if the protein concentration Dumbbell-shaped bands oris known.smiling bands Uneven surface of the resolving gel Try to make the resolving gel surface even while pouring the gel.Use the gels before the specified expiration date. Note: NuPAGE gels Expired gels have an extended 12-month shelf life, minimizing the risk of having expired gels.76'