Thanks to all who sent in helpful responses to my query regarding the 
ABI 5x sequencing buffer. It appears that most people use the 
following recipe. Indeed it seems that it is just  400mM Tris, and 
10mM MgCl2, pH 9.0 solution, making it one of the most expensive 
saltwater solutions in the world.

Some of the more helpful responses are pasted below. If you're buying 
this from ABI, you should complain to the bitterly about their 
exploitive business practices.

Cheers,
Paul

From: Tomas Hrbek
Cycle sequencing 5x replacement buffer (1 liter):

400 ml 1M Tris-HCl pH 9.0
10 ml 1M MgCl2
590 ml milliQ H20

Stir for minimum of 1 hour. Filter though a Watson filter paper. Aliquot
into 15ml conical tubes. Store at 4C or room temperature.

From: Brant Faircloth

the solution that i have for 5X BD dilution Buffer is 400mM Tris-HCl 
(pH 9.0) and 10 mM MgCl2, just as you wrote.  It can be used with BD 
3.1, and we run 12th or 16th reactions.

S. Lin and Bruce Roe list the same solution for BD 3.1 here (for a 
1:64 dilution; 96-well plate premix):

http://www.genome.ou.edu/PredispensedDilutedSeqMixBD3orET.html

and you can also find the same buffer solution recommended on the 
(very pretty) barcodeoflife.org site (protocol from the CCDB):

http://www.barcodeoflife.org/CCDB_DOCS/CCDB_Sequencing.pdf

U. of Washington, however, lists their BD buffer (for 1.1 and 3.1) here:

http://dnaseq.bchem.washington.edu/bdsf/help/dilutions.html

as (I have shown 5X below):
350 mM Tris (pH 9.0) and 2.5 mM MgCl2

not sure about this one, but I figured you might want to see some options ; ).

cheers,
b

-- 
Dr. Paul H. Barber
Boston University
Boston University Marine Program
5 Cummington St.
Boston, MA  02215
617-358-4589 office
617-358-4590 lab
617-353-6340 FAX
pbarber@bu.edu
http://people.bu.edu/pbarber/

Paul Barber <pbarber@bu.edu>