How to concentrate DNA - (Jul/05/2012 )

Hi,

I would like to concentrate my DNA sample.
At this moment, i'm trying to maximize my DNA sample during extraction, by using low elution volumes and a higher amount of input material.
By doing this my concentration enhanced from 68 ng/ul to 156 ng/ul.
Is there an additional solution to enhance my DNA concentration besides lower elution volumes?

cheers,

Susan

1. Warming elution buffer (upto 55 C) may greatly enhance the yeild sometimes.
2. Holding elution buffer 1-2 minutes before centrifugation (if this step required like in miniprep) is also recommended.

You could use Amicon units. They are supplied by Millipore:
http://www.millipore.com/catalogue/item/ufc503096
http://www.millipore.com/catalogue/item/ufc5100bk

These have 30kdalton and 100kDalton cuttoffs but they also do other cuttoffs depending on how long your DNA is that you want to retain.
Here's the brochure:
http://www.millipore.com/content-page.do?url=/userguides.nsf/a73664f9f981af8c852569b9005b4eee/859e4d359e35eddd852575b7005e90a6/


I used to use their predecessor, the Microcon, to great effect and I don't suppose the Amicon is any less capable. They're not inexpensive but they can concentrate DNA well and also help get rid of salts and other contaminants.

Thanks, i'll try it out

You can also try larger elution volume first to increase the DNA yield and then can (1) precepitate the DNA with ethanol/isopropanol or (2) dry the whole eluent in chilled vaccume evaporator (eg. SpeedVac) and dissolve the pellete/dried sample in the minimum volume of water/TE to have higher concentration

rmbio,
so after eluating DNA, i just have to add ethanol/isopropanol to the eluaat? How many?
Do you have a protocol for this?
thanks!

Protocol is pretty easy to follow...
1. Add equal volume of chilled isopropanol, mix and incubate at -20 C for 30 min
2. Pellet down the DNA by centrifuging at 10000 g / 10 min / 4 C
3. If you have used elution buffer (usually TE) for elution, give 70% ethanol was to the pellet (add 1 ml 70% ethanol, incubate at RT for 5 min, spin 10000 g / 10 min / RT). If you have used water for elution, no need to give 70% ethanol wash
4. Dry the pellet (after complete removal of the supernetant using pipette) at RT for 10 min
5. dissolve in the desired volume of water/buffer

Thanks

don't forget to add salt (the 70% ethanol wash is to remove residual salt after pelleting).