Date: Thu, 09 Jan 1997 15:34:19 -0700 (MST)
From: "Terry Mulcahy 272-5792; fax 272-9107" <TMULCAHY@medusa.unm.edu>
Subject: DNA Synthesis
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Date: Mon, 28 Oct 1996 12:50:38 -0500 (EST)
From: MTALMOR@biomed.med.yale.edu
Subject: Trityl monitoring, point restrictors
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From: BIOMED::MTALMOR 28-OCT-1996 12:48:42.35
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Subj: Trityl monitoring
I have 2 ABI 394's with automatic trityl monitors, and my experience is that
this monitoring is certainly better than no monitoring, but it is not an
absolute quality control mechanism. I have been able to identify "bad"
amidites, certain reagents running out, dirty point restrictors, and a valve
block problem, but this is only possible if you monitor all all the couplings
and keep a few weeks' worth of readings in order so you can look for patterns.
After the first 20 or so bases, the trityl values are meaningless, because
(according to ABI), the values recorded are from the side reactions more than
from the actual synthesis going, but they are still indicative of catastrophic
failures. That's why they go up after 20 bases. My feeling is that it's still a
better system than having to deal with a fraction collector and "eyeing" the
tubes, but it's still far from perfect. BTW, these limitations are discussed in
the instructions which come with the monitors, and they were also explained to
me by the service engineer who installed the instruments.
As for point restrictors, they are cleaned by boiling in water for 10-20
minutes, then sonicating in methanol for the same amount of time. It is
important to keep a set together, however, not to mix different sets. My
service engineer was very useful in explaining all this.
Monica Talmor
Path. Dept. DNA Synthesis Lab
Program for Critical Technologies in Molecular Medicine
Yale University School of Medicine