3 replies to this topic

[natic]

I'm using Promega's kit for gel purification of DNA fragments. When Im tryng to run a sample on gel after purification, the sumple is running out of the well very fust... this shows that there are ethanol residues in the sample.
I have tried to spin the column in a higher speed and more time, but still, there is ethanol residues there...

Did anyone have the same problem?

[methylnick]

Hi Natic,

I use this kit all the time. To ensure the column is dry I usually centrifuge at maximum speed for at least five minutes to dry the column after the second ethanol wash, I remove the wash fromt he wash tube and then spin again for 2 minutes at maximum speed.

I have had this problem before when the DNA sample floats out of the well upon loading adding this extra step by removing the wash and then centrifuging again makes things better.

good luck!

Nick

[leahf]

i've never used promega's kit for gel extraction, only quiagen and roche which work fine, but:
its very important to do an extra spin step to your collumn after the the wash step - throw away the flow-through, and spin the collumn, dry, for another minute.

[fred_33]

hi
i use this kit and after the last centrifugation, i make an additionnal 5' top speed centrifuge and let the column dry RT 30' or 37°C 10' (98°F). I use to make 30' RT due to the fact for miniprep purification (promega kit) drying at 37°C reduce the elution efficiency.
hope being little useful
Good luck !