Cleaning up oligos

[Udo Reischl]

In article < Sun, 15 Jan 95 17:0:11 UT / patterson at cvlab.harvard.edu 
> 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.

Dear Cam,
We use NAP-10 columns (e.g., Pharmacia) to desalt our oligonucleotides. 
Following cleavage and deprotection in 1 ml conc. ammonium hydroxide, the solution 
is applied to the column and eluted with 1,5 ml H2O. Oligonucleotides 
purified this way are working fine in sequencing experiments. If a 
higher degree of purity is required, organic by-products of the 
phosphoroamidite synthesis can be removed by vortexing with 1/1 volume of 
H2O-saturated 1-butanol prior to the desalting procedure. 

Hope this is of help,
Udo