Dear all,

I have trouble with an increasing peak broadening and tailing for a sulfoxide only after a few injections of soil extracts (80% MeCN). I run full water/acetonitrile gradients with 0.1% HCOOH and see no backpressure increase or contamination of my precolumn filter. Replacement of the precolumn filter did not change the picture.
I already tried to recover the performance of the column (Agilent ZORBAX Eclipse XDB-C18) with EDTA without any success.

Thanks a lot in advance
Tom