DNA ladder does not resolve well - (Aug/21/2013 )

I was using 1 KB DNA ladder plus. The ladder separate very well but I have to use 1 KB DNA ladder now. B it dose not separate as good as the other one. I tried different concentration of it but it doesn’t make any different. By the way, both ladder are from a company. Any comment regarding this issue? thanks

If you can tell us exactly which conditions you have tried, that will help us to diagnose the problem.

How old is the ladder, and how has it been stored? 
Is there someone else who is using the ladder successfully?

Thank you bob 1 for your replay.

Actually I tried 1, 1.25,1.5.1.75, 2, 2.25, 2.5 μg of ladder but it doesn’t separate nicely.

I used 0.8 & 1% agarose gel.

Three other students have this issue too.

The ladder is 6 months old and it is in -20.

It is possible that you are using too much DNA per lane, I usually use 50 ng per mm of lane width (i.e. the width of one tooth on the comb).

With 4 people using it and repeatedly freeze/thawing, it is likely that some degradation is also happening.  If you get a new one, try storing in the fridge or aliquoting.

thank you for comment.

I will take a new one and will load and see what is going on.