David T. Chin
UMC Protein Core
e-mail: bcdchin@muccmail.missouri.edu
(573)882-2027 (office and messaging)
Dear ABI 430A experts (I hope there are some left!):
I'd very much appreciate your thoughts/suggestions on how to solve a problem
with our 43OA synthesizer. We've kept the machine in good working order and use
it routinely for Boc chemistry. Recently we have detected serious failures with
the small-scale rapid cycle (0.1 mmol) program, leading to largely incomplete
couplings. The problem exists only with this program. Runs using std1 files DO
NOT present any problems. A brief summary of our prognosis follows:
1. System checks for the A, B and C regs are OK. TFA and DIEA deliveries are
accurate. Boc-AA is correctly dissolved.
2. DCC and HOBt are measured and delivered OK.
3. Activation proceeds OK (DCU precipitation observed)
4. ACT to CONC and CONC to RV transfers are OK.
5. Problem subsists when a new (from PE) disk with SSRC is used
6. Problem is independent of resin type (Pam, MBHA)
The local PE technicians seem a bit at a loss with the problem. Does anybody
out there (perhaps PE people on the list) have a suggestion? Thank you very
much for your attention.
David Andreu
University of Barcelona, Spain