FAQ: What should I do if I see adaptor dimer in my NEBNext UltraExpress™ libraries?

The phased cleanup step following PCR is specifically designed to reduce adaptor dimer; please follow the instructions for this step as written before attempting any additional recommendations.

If you still see small amounts of adaptor dimer in samples, we recommend a 0.9X SPRI bead cleanup after pooling libraries or further optimization of the adaptor amount.