Clogged G-amidite lines

[Karen]

In article <B600DA2E01B938D9 at office.mmc.org>, varyc.mmcri at OFFICE.MMC.ORG
(Varyc) wrote:
> 
> Hi netters,
> I would like to know if users of the ABI DNA synthesizers have been plagued with the precipitating
> G-phosphoramidite line problem. And, if so, what lor surrounds this problem and is there a fix?
> 
> Cal Vary
> MMCRI

Apparently this is a well known and widespread problem. We have tried a
number of things based on the advice of the ABI people. All to no avail. We
were optimistic a while back that diluting the phosphoramidate when we
switched to the 0.04nmole columns might help a bit, but no such luck. We
also tried using only phosphoramidites synthesized since Jan of this year
when some new trick was apparently tried with the synthesis but also no
luck. We have tried the low temperature hypothesis, the humidity hypothesis
etc etc but found no consistent factors that we could identify. The last
advice ABI gave us was to take the bottle off the machine if the machine
was going to be idle for any length of time [The remaining solution can be
stored in a dessicator at -20C until needed].



Karen Usdin
Section on Genomic Structure and Function
NIDDK, National Institutes of Health