Oligo stability in water at -20 C

David L. Haviland, Ph.D. dhavilan at IMM2.IMM.UTH.TMC.EDU
Tue Aug 11 10:28:21 EST 1998

At 14:33 8/10/98 GMT, Chris Boyd wrote:
>We are currently suffering from an oligo problem such that some (too
>many in fact) oligos stored at -20 C for six months or more are found
>not to work for PCR (sometimes even when UNUSED). On HPLC analysis we
>can clearly see degradation of the enfeebled oligos. Legend has it that
>this didn't used to happen with a previous supplier's oligos. Most
>people here follow the current supplier's recommendation and dissolve
>the oligo (supplied as a dried down pellet) in water before freezing. 
>Others use TE. Could it be that water-dissolved oligos will go off
>faster than buffer-dissolved oligos (even at -20 C with no thawing) due
>to (eg) autohydrolysis? Has anyone any data on this, or any other
>thoughts about oligo stability? I see no reason why oligos that are OK
>to start with, and stored in suitable sterile enzyme-free media,
>shouldn't last for years.


As far as lasting for years, they do!!!  Will agree with aspects of
previous posts that it really depends on the quality of what was used to
resuspend them.  We have been using TE (that is 0.1 mM EDTA), autoclaved
mili-Q water, as well as DEPC-water for oligos used in RNA work.  Nucleases
from "sources" are always a concern as is freeze thawing.

So far we have been lucky as I've had need to pull out oligos that were
kept at -20'C since '93.  So far, those that I've used (about 6 of a total
of about 80) have worked just fine for PCR and automated sequencing.


 David L. Haviland, Ph.D.
 Asst. Prof. Immunology 
 University of Texas - Houston, H.S.C.
 Institute of Molecular Medicine  
 2121 W. Holcombe Blvd.  
 Houston, TX  77030 
 Internet:"dhavilan at imm2.imm.uth.tmc.edu" 
 Voice: 713.500.2413  FAX: 713.500.2424
Never take life seriously. Nobody gets out alive anyway.

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