Dual indexing in general, which uses both i7 (Index 1) and i5 (Index 2) indices, enables multiple RNA-Seq libraries to be multiplexed for in a single sequencing lane or run. Using dual indexing, the combination of both i5 and i7 indices determines the unique barcode combination for sample identification and increases the accuracy of read identification when the sequencing data is demultiplexed.
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Index hopping can also be controlled by repurifying library pools prior to sequencing to remove excess adapter dimers and free index primers. Lexogen’s Purification Module with Magnetic Beads (Cat. No. 022.96) can be used for this repurification step. Briefly, add 0.9 volumes of Purification beads (PB) to the library pool, mix well and incubate for 5 minutes at room temperature, then follow steps 30 onwards in the QuantSeq User Guide(015UG009) Detailed protocol (see 015UG009 for protocol details)further details, or contact support@lexogen.com.