Help: Desalting Oligos

Dr. Duncan Clark duncan at
Thu Nov 21 11:55:50 EST 1996

In article <jabbott.1.32932B8E at>, JAMES ABBOTT
<jabbott at> writes
>Can anyone out there help me?
>We have some PCR primers which contain a high concentration of salt (Don't 
>ask - you'd only laugh!), which would appear to be precipitating PCR reaction 
>mixtures and preventing the reaction from proceeding. Does anyone know a 
>cheap and dirty method of desalting small quantities (200 nmol/ml) of oligos 
>(14mers-25mers) without too much loss of DNA.

Ethanol pption using 2.5vols and no extra salt? 
G25 gel filtration or a G25 spin column.
Dilute the salt even more with 10mM NaOH and load onto a monoQ FPLC
column (or similar). Elute with a salt gradient of 0.6-1.1M NaCl in 10mM
NaOH. Pool peak and ethanol ppt.

The problem with being on the cutting edge is that you occasionally get 
sliced from time to time....

Dr. Duncan Clark
DNAmp Ltd.
TEl/FAX 01252376288

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