Pharmacia ALF problem

David Spodick dspodick at
Fri Jan 27 23:03:18 EST 1995

Jeffrey Keen (t.keen at wrote:
: Has anybody had the same problem as me with their Pharmacia ALF sequencer?

: What has developed is that I am getting a very high peak of fluorescense
: (way off scale) passing through the gel just before the primer peak.
: Pre-running the gel appears to allow the contamination to pass through the
: gel before loading, but still leaves a residual background of around 45%.
: The fluorescense isn't noisy so doesn't affect the sequence (as far as I
: can tell anyway).
: I've stopped using our own RO water and just use Merck Analar stuff
: without getting rid of the problem. Swapping detergents doesn't seem to
: help either.

: Any suggestions 

: Jeffrey Keen
: t.keen at


I am currently at a meeting of ALF specialists for North America.  We
haved discussed your problem and would like to follow up with a few
questions.  How many times has this happened?  Does it matter what primer
you use?  What kind of gel are you running (acrylamide or LongRanger)? 
Have you changed any gel components lately?  It is possible that certain
batches of APS or Urea may have some of the contaminants that you

You can respond to me personally or through this newsgroup.

David Spodick, 
ALF Specialist
Pharmacia Biotech
dspodick at

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