Sonication woes

[Selbbub]

Hi everyone,

I am having some difficulties optimising sonication and would like some advice I am trying to sonicate approx. 12 million cells in 1.5ml lysis buffer using a Sonics Vibra Cell. I'm currently using 40% amplitude and 10 sec bursts, however after 40x10 seconds my chromatin is an even smear from 200-2000 bp with no concentrated region. This size range so far seems to be working for regular ChIP, but obviously isn't anywhere near small enough for ChIPSeq.

It seems like I am already sonicating a lot compared to what most other people need to do.. any suggestions?

[jo_4]

Hi selbbub,
What kind of cells are you using? Does your lysis buffer have 1% SDS? Trying to reduce the volume to 600ul might work..