# What volume of TruSeq RNA UD indexes should be used during TruSeq Stranded RNA library preparation?

The volume of TruSeq RNA UD indexes used at the Ligate Adapters step of the TruSeq Stranded mRNA and TruSeq Stranded Total RNA protocols is **2.5 µl for each sample**. The TruSeq RNA UD indexes are available as pre-paired i5 and i7 index adapters in each well of a 96-well plate.

**Note**: Index adapter plates include significant overfill, so it is critical to add the 2.5 µl of adapters into each sample (to the sample plate) rather than adding samples to the index adapter plate.

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