What's your downstream application? Do you really need the highest quality DNA. I've used DNA with 260/230 ratios of 1.5-1.7 (when desparate!) for PCR based application without issue.

It is for Next gen sequencing. Illumina and MinION.

I think should aim for higher than 2. Some samples are lower than 1.

Perhaps this might help!

Biotechniques. 1992 Jul;13(1):52-4, 56.

A quick and inexpensive method for removing polysaccharides from plant genomic DNA

Hi Marcus, I tried the protocol (https://goo.gl/YBRdP7 ). But I got the same ratio on 260/230.

I did another chloroform isoamyl 24:1 purification and got the same result.

I have no idea what is going on.

Maybe try a standard silica column based purification kit though I've no idea about the interaction between polysaccharide and sianol groups (I'm afraid I've no experience specifically trying to eliminate polysaccharide contamination from DNA samples). I think the Ampure beads are more suited to PCR fragments, I could imagine genomic DNA creating a vicous mess resulting again in contamination issues.

Perhaps someone else can contribute here!!!! Good luck.

Hi, I think you could use the DNA Purification Kit ,The DNA could be purified.

Hi, I think you can used doyle & doyle DNA extraction protoclol is perfect good quality and pure DNA obtained.

Hi,

Try checking Zymobiomic, they have decent genomic DNA extraction kits.

Also if you are measuring Genomic DNA is it not 260/280 ratio =1.8 ?

Try incubation the DNA with proteinase K and RNAse. This should get rid of any carry over proteins and RNA.

What purification method did you use? Many of the commercial DNA purification kits use chaotropic salts which have an absorbance at 230 nm. An additional Ampure purification may help whether it is salts or polysaccharides. Keep in mind that all library protocols have bead based cleanup steps too.