Can I sequence libraries prepared from cfDNA together with libraries prepared from FFPE DNA?

This is possible; however, it is relevant to note that the read length you set may alter from your usual parameters. cfDNA is on average 166bp in length therefore, we usually recommend 2x75bp read length. For FFPE DNA fragments are often longer, and we would recommend a 2x150 bp read length. If you run at the longer read length you will sequence into adapter sequences and need to remove these during analysis. Alternatively, you can sequence all your libraries at the shorter read length of 2x75bp, however, this will impact the achievable depth of coverage for your FFPE DNA libraries.