Hi Sonali,

I believe ethanol will precipitate genomic DNA and dissolve salts, keep them away from your DNA. If you still worry about salt contamination, I often do 100% ethanol precipitation follow by 75% ethanol wash, dry DNA precipitation at room temperature for 5-10 minutes and dissolve in nuclease-free water. 

You can do an extra step by repeating the ethanol precipitation step after that.

I did nano drop after that as well and saw a nice peak at 260nm and A260/A280 around 1.80-2.00 for DNA samples. The graph also looks nice and I believe most salt in the final sample has been removed.

Best,

Sodium acetate helps in precipitating the pigments and tannins present in the homogenate. Ethanol washing helps in removing the salts and detergents associated with the DNA pellet.so after all steps with sodium acetate and ethanol still your DNA pellet was not free with salts then you have to repeat the wash with 500ul of 100% Ethanol . ( EMSURE R ACS ,ISO, Reagent.Ph Eur Ethanol. Company Merck).

Dear Sonali

If one of you buffers have precipitated during extraction heating your sample to around 37 - 40 degrees Celsius will dissolve the precipitate.  You can then concentrate your DNA using ice-cold 100% ethanol.

I hope this helps.

Good luck!

i agree with above answers..as i told you earlier also try with 500ul of your sample and precipitate your dna again..do the final precipitation and washing steps again and this time dissolve in pure water and then check the 260/280 values ...good luck...