Date: Thu, 09 Jan 1997 15:38:04 -0700 (MST)
From: "Terry Mulcahy 272-5792; fax 272-9107" <TMULCAHY@medusa.unm.edu>
Subject: DNA Synthesis
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Date: Fri, 01 Nov 1996 18:25:11 -0800
From: williams_l@froggy.hsc.usc.edu
Subject: trityl monitoring
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Had to go back in my notes for this one!
Back in July 1993 we purchased an extended capacity, autoanalysis 394 which
was installed in the lab. The conductivity readings ranged from 93 to 97.
We were not happy, and the trityl readings for the repetitive yield weren't
reassuring either. We were told that all installation data was obtained on
the 0.2um scale and the 40nm scale was not dependable, so we switched to the
0.2um scale, but these readings weren't very much better.
Since we didn't agree with the installer's feeling that all was fine, we did
some further checking and found that the Burdick & Jackson DCM moisture
content was 0.004 (ABI was temporarily "out" and did not send any with the
start up kit). Further investigation revealed this DCM was going through the
column immediately prior to the TCA removal of the cyanoethyl protecting
groups with no reverse flush in the interim, leading us to assume moisture is
in the vicinity of the unprotected base at its most crucial time. Also, some
ABI DCM was ordered, but it came with no moisture content noted on the
bottle.
We decided that even if the auto analysis WAS functioning properly, we had
reservations about it, since it consumes large amounts of DCM, which is more
hazardous and more expensive than acetonitrile, even the low moisture B&J
that we routinely use.
So we keep a bottle of DCM on our useless appendage and pay $200 more a year
on its service contract. Otherwise, the machine works very well.
Lynn Williams tel: 213-740-0541
541 Norris Cancer Center/USC fax: 213-764-0091
1441 Eastlake Ave e-mail: williams_l@froggy.hsc.usc.edu
Los Angeles, CA 90033