Yes, the UMIs are random 6 nt sequences that will be added to all samples. Therefore, the UMI sequence cannot be used to uniquely identify the different samples – only to tag distinct random priming events during library generation.The i7
(and i5) indices Learn more about UMIs, their function, and usage in our Lexicon Chapter #8.
The 12 nt Unique Dual Indexes (UDIs) are still required if multiple libraries need to be uniquely barcoded and pooled for sequencing in a single lane or run. The i7 and i5 index UDI sequences are added during the endpoint PCR and read-out during sequencing with index reads 1 and 2, respectively. The index reads are required for sample demultiplexing after sequencing.
The i7 indices UDIs required for the final amplification of QuantSeq libraries are included as a bundle in every QuantSeq Library Prep Kit . Alternatively, 12 nt Unique Dual Indices (UDIs) can be used to enable uniquely dual-indexed libraries for Illumina sequencing. QuantSeq Library Prep Kits and UDIs are available in bundle versions (Cat. No. 113 – 115, 129 – 131s 191 - 196).