I've been facing a problem in DNA agarose gel electrophoresis. My low molecular weight bands ( and bromophenol blue dye ) appear as curve bands ( frowning not smiling ) . I am using a fresh 0.25x TBE . 2.5% agarose ( 20 cm x 20 cm x 5 mm ) . My agarose is prepared in also 0.25X . The voltage I am using is high ( 8 V/cm ) but the current is only 40mA so there's not any excessive heat generation . The electrophoresis run is short ( only 30 minutes ) . I tried different samples , fresh buffer , higher buffer concentration , lower voltage . But still the same . The bromophenol dye appears as a sharp curved band ( frown ) as soon as it enters the gel.
I get the same problem in all different lanes of the gel .
I wonder if it's because of poor gel preparation . I always get bubbles trapped in the gel ( very very tiny bubbles but there are thousands at some spots ! ) . However , the region ahead of the wells seems very clear so I don't think this is the problem .
I don't know what to do ...any help would be appreciated
thank you in advance
