Methods for concentrating plasmid DNA - (May/09/2006 )
I've got a plasmid with a low concentration from a MaxiPrep (it didn't work really well). Could anyone figure out how I can get it more concentrated? What I mean is I have got 200ul and I would like to get it conecntrated only in 30ul without doing again MaxiPrep.
Thanks in advance.
precipitate with your favorite solvent and resuspend in a smaller volume
How silly I am.
About the solvent, can it be isopropanol 100% and then Ethanol to wash the pellet?
What other solvents are interesting?
Thank you very much for your quick reply
I think ISOH and ETOH are fine...make sure to wash with 70% etoh/h2o but I bet you already know that
I use ETOH/NaoAc, followed by a wash....I think Fred has a butanol method, although I don't know the details? if you search for "concentrate DNA" on this site you will probably find a variety of methods
good luck 
hi
i like butanol method for small quantities or for quick pelleting. It works by dessication of the solution.
Add roughly 8-10 times your sample volume, vortex 30'', and spin top speed for only 5'. Wash in grzeat volume of ethanol 70% (2times may be necessary).
Let solvent dry and resuspend in smaller volume.
Thank you very much for the help.
It's always good to know various methods. I go for Isop and Ethanol 70% just because I have already the reagents but I don't get good results next time I will try one of you both propose.
By the way, I confess I forgot to do the search before sending this post. Next time, I promise, but, you know, sometimes it's difficult to find what you are looking for because the words need to be exactly those used in the past post.
Cheers.
hi gsamsa ! alcohols precipitate nucleic acids and the precipitating capability increases with the Carbon content of the alcohol. i.e., methanol< ethanol< Propanol< butanol....... but as the C no. increases evaporation becomes more difficult. ethanol and isopropanol are very good precipitating agents for nuceic acids and also evaporate quickly. but these methods though rapid are associated with sample loss.
if you have small quantities of sample and you want to concentrate it and store it, i think lyophilization is the best method.
all the best
yes but lyophilization may cause DNA/RNA shearing
hi Fred ! you are right but for small dna molecules like plasmids , primers etc.lyophilization method is suitable and when the objective is just to concentrate and not dryout the sample then it works fine i suppose. also speed vacc. is another method.
May I ask some silly question!.... Do i need to resuspend the DNA pellet while washing with the 70% EtOH? or I must not disturb the DNA pellet???
Thank you