Library prep/low concentration

[Normal]

Hi all,

I'm a new member in this forum. I'm having trouble with preparation of my sample using Nextera XT kit. Most of my samples came out with too low concentration after PCR cleaningup. I checked my starting DNA conc (e.g for 2.25ng/ul, I used 0.44ul sample). I don't have problem with my cleanup process but the library yield is always coming out too little for sequencing. Please, I'd appreciate anyone with valuable suggestions.
Thanks

[nucacidhunter]

Two cause to consider:
1- Accuracy of quantification and method used
2- Library fragments were too short or bead ratio was low and fragments were removed during clean-up. Checking size distribution before clean-up should rule in or out this assumption.

For better help please post Electropherogram of few libraries.