Plasmids purification - how to remove DNA contamination (Feb/01/2002 )

I have purificated DNA with QIAGEN kit, but sometimes (i don't know why) I have contamination of this preparation . the 260/280 ratio is between 1.8 and 2 , but when I try to make a calcium phosphate precipitated it doesn't appear.
How to remove the contaminant (probably LPS..)of the preparation of plasmids? I heard about using Triton, how to do?

-nicolas cazeaux-

It's about transfection, right? What Qiagen kit have you used? You might want to try their 'Endofree plasmid kit' which removes LPS.

-Cthulhu-

Why not you use the Eppendorf 5 prime perfect prep plasmid kit instead. This kit can be used directly for the transfection work.This kit does not use orgnic solvent and hence will be well suited for your application

-sankar-

Aldevron's RedStar system effectively removes LPS from plasmid preps and provides transfection-ready DNA. Please see http://www.aldevron.com for details. I will be happy to arrange for a free prep if you would like to evaluate the service.

Best regards,

Michael
chambers@aldevron.com

-aldevron-