We have an old sequencer model PE-ABD 477A and we are experiencing low
repetitive yields but normal low leg and normal artifact peaks. All
deliveries are properly optimized and the reagents are all under the
expiration date. We already check the internal diameter of the reaction
cartridge input and output lines, the temperature of the cartridge, the
argon pressure and the vent lines. We flushed all the chemical delivery
system with R3 (TFA) and S4B (acetonitrile 20%). Apparently there is a leak
in the TFA delivery valve. We saw this moistening a pH-sensitive paper,
placing it beside the open end of the cartridge inlet line, and delivering
argon through the E block onto the paper. The observed pH was lesser than 3,
which indicates leakage in the TFA valve. However, two details are bothering
us: first, the E block is new and is being used for the first time. Second,
pressurizing the block with the TFA bottle out, using the regulator to make
the test, one does not verify a leak. I now have some questions to experts
in 477A. Can a new valve block leak? If argon dry is dragging TFA, or
either, if there is a leak from the TFA bottle to the block, how can the
block not leak in the contrary direction, I mean, from the block to outside,
when the bottle is removed? Do somebody have any suggestion to solve the
problem of the low yield?
I am anticipatedly thankful.
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Prof. Ricardo B. Cunha
Brazilian Center for Protein Research and Services - CBSP
Laboratory of Protein Chemistry and Biochemistry
Institute of Chemistry
University of Brasilia
Brasilia - DF Brazil
ZIP: 70910-900
Tel: 55-21-61-307-2142
Fax: 55-21-61-272-4548
mailto:rbcunha@unb.br
http://www.geocities.com/Athens/Acropolis/5221
http://www.unb.br/cbsp
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