The Genome and Exome workflows use different volumes of SPRIselect beads for post-GEM clean-up. This is because the Genome post-GEM SPRI cleanup targets a larger fragment size, whereas the Exome post-GEM SPRI cleanup targets a smaller fragment size.
In order to capture smaller DNA fragments, the ratio of SPRIselect beads is higher in the Exome workflow (1.2x) than in the Genome workflow (0.7x). We perform two SPRIselect steps in the Exome workflow because the higher ratio of SPRIselect beads is less effective at removing the carryover Gel Bead oligo primer.
Note: Further information on Gel Bead oligo primer carryover can be found in a Technical Note on our website (https://support.10xgenomics.com/genome-exome/library-prep/doc/technical-note-chromium-genome-v2-libraries-gel-bead-oligo-primer-contamination-affects-sequencing-and-application-performance).
Products: Genome, Exome