The pump block needs to be cleaned when:
Installing a syringe.
Switching applications (i.e., from sequencing to fragment analysis).
Shutting down the instrument for a long period of time.
If the instrument has run for more than 4 days without any of the above occurring.
Appearance of unusual spikes in the electropherogram.
If the syringe containing the polymer has been on the instrument for more than a week, it is important to clean the syringe and the block, and to change the polymer. At room temperature, enough urea decomposition can occur in one week to cause transient current increases during electrophoreses. If polymer is allowed to dry in the pump block channel, the pump block may be ruined.
Find additional tips, troubleshooting help, and resources within our Capillary Electrophoresis Instruments Support Center.