Sharp peak in amplified RNA library

[gman85cini]

Hey everyone,

So i've been trying to make libraries from low-ish input (i.e.: 25-50ng total RNA) using Linearized DNA Amplification and NEB Next Ultra. RNA was polyA selected and fragmented. I'm getting this weird sharp peak at ~330 bp (see attached) after amplification (19 cycles) and I'm not quite sure what to make of it. Looking for any thoughts or suggestions. If you need more details let me know.

Thanks!

Giacomo

[nucacidhunter]

Providing more info would enable others to offer more comprehensive help. Not knowing the details of your library prep method, one possibility is contamination of libraries (or reagents used) with an amplicon possibly one flanked with Illumina adapters that has been amplified efficiently.