sequencing problem

Recently, we upgraded our Applied Biosystems (ABI)3100 DNA Sequencer to an ABI3130XL system. We are sequencing with 50cm capillaries and POP7 polymer.

When running sequencing reactions (BigDye v3.1), we generate profiles with following characteristic: at the end of the sequence we often registrate an A-peak with (very) strong intensity >> the more when sequence length is shorter. This problem is observed with XTerminator and other purification technologies.

Do you have any explanation for this?

It sounds like it might be a signal spike caused by an air bubble in the capillary. Take a look at this page [www.nucleics.com]

If you send me the trace I will take a look at it and let you know.

Cheers

Daniel Tillett
Nucleics Support

Thanks for your quick reply. This problem always occurs at the end of the sequence. A profile has been sent by email.
Regards,