How long will labelled oligos last?

[Jerry Kropp]

In article <58kdlo$bqg at dfw-ixnews12.ix.netcom.com>,
sendero at ix.netcom.com(Dr. Michael T. MacDonell) wrote:

> Bill:
> 
> I'll admit my first inclination was to lurk and see what other folks had
to say
> about this, but I realized that what would most likely come back would be
> "theoretical" answers.  Theoretically, it should last a very long time.  In
> practice, however, it is likely to be a different outcome.
> 
> People who have a lot of experience making oligos (I have personally made
> probably in the neighborhood of 50,000), find that synthetic oligos seem
to have
> a half-life.  The most sensitive application seems to be PCR.  This is curious
> since the restriction enzyme recognition should be the most sensitive, but it
> doesn't appear to be.  Frequently we have found that an oligo that performs
> beautifully as a PCR primer, will perform only acceptably after 8-9
months, and
> may not prime at all after 18 months.  We have stored the oligos dried down at
> room temperature, as -20C, in sterile water at -20C, and in 20% (v/v) MeCN at
> -20C.  The outcome is approximately the same.
> 

Hi Mike:

Back when I was making my own PCR primers (it made economic sense then) I
took to storing them in sterile 0.5X TE at 4 degrees at a conc. of 25-100
pmol/ul. The TE thing was arbitrary. The 4 deg. was due to my fear of
freeze-thawing. I didn't aliquot out of sheer butt-indolence. Some of
those puppies are nearly 10 yr old and still support amplification.
Likewise, some of them don't. Most do, however.
I have some you guys made for me (blatant plug) that are still good after 2 yr. 
If I think a primer has gone sour I run ~100pmol on a native 10% PAGE (no
need for denaturants, in my experience) along with a standard oligo that I
know is good. Stain 'er with ~2mcg/ml EtBr. Should get a fuzzy band, if
good.

This by no means a rebuttal of your much greater experience. Maybe I've
been lucky.

Cheers,
Jerry

Oh, and thanks for the advice that you have been so generous with in the
past. (Blatant plug #2--maybe I'll get a free oligo out of this). ;)

-- 
no brains...no headache!