Clean up high weight artifact visible in Bioanalyzer HS?

[Kwafelenge]

Hi All,
I created some amplified cDNA and we notice some artifact above 10,000 on the Bioanalyzer plots; see:

https://docs.google.com/file/d/0B_2HVSBwoWY3N1NxenRkdXZNdTg/edit?usp=sharing

It's most profound on the first sample, but is apparent in all 3.

I'm considering using the first part of a dual-SPRI bead size-selection procedure, where I use a small volume of beads to bind only the large stuff, and then recover my sample from the supernatant.

But I'm not sure of a good volume of beads to use.. Thinking it should be much lower than 1x the volume of the sample in water. But how low? 0.2x? Higher? Lower?

Thanks for any help!
Jon

[Kwafelenge]

No suggestions from anybody out there?!

[BobS]

AMPure XP

Hi

We use 0.4 vol, AMPure XP beads to sample, to bind ~2kb+ fragments, that's with a 15 min. RT incubation / mixing. I tried to titer the beads once , it seemed it was all or nothing up to 0.4 vols, But your second peak is larger, at >10kb, than the DNA I was working with.

Good luck