Cleaning up oligos

Lawrence Washington lwashing at
Mon Jan 16 13:56:18 EST 1995

In article <patterson.1140560394A at>,
patterson at (Cam Patterson) wrote:

> We recently purchased a Beckman DNA synthesizer, and I find
> that the oligos we create work fine for PCR and for labelling
> but not as well as commercially produced oligos for double-
> stranded DNA sequencing. I suppose we need to desalt our oligos
> and I am wondering what people have found to be the quickest
> and easiest method to do this effectively. Any help is greatly
> appreciated.

For quick and easy desalting we use disposable reversed-phase C18 columns
(many companies make a version of these; SepPak from Millipore or BondElut
from Analytichem, for example).  Very quick (a minute or two, not counting
evaporating off a little methanol at the end), very easy (I trained my pet
monkey to do it).
You may find, however, that you also need to remove the incomplete oligos
from the mix that comes off your synthesizer.  There are several ways to
purify oligos, but that is another whole issue.

Lawrence Washington
Indiana University
Institute for Molecular
 and Cellular Biology

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