Unincorporated dye terminators and residual salts must be removed from the extension products. The 3130xl capillary sequencer is especially susceptible to salt in samples.
The LGT strongly recommend implementing an efficient method to remove excessive salts. This is done by preparing a commercially-available spin column, ethanol/EDTA precipitation and BigDyeXTerminator (http://tools,thernofisher.com/contents/sfs/manuals/cms_081527.pdf). The eluted product is dried down in a speed vac and resuspended in deionized formamide. The LGT supplies the formamide to all sequencing users and has a Savant DNA speedvac available.
Large-scale (ABI 96 well MicroAmp plate) users can purify the extension products by ethanol/EDTA precipitation protocol.