Precipitate DNA with PEG

2X Precipitation Solution:  40% (W/V) PEG 8000, 20 mM NaCl2

To DNA solution add 

 PEG concentration of 13% in the presence of 10 mM MgCl2 at room temperature (20-22°C).

  5-10% (w/v) PEG 8000 ,  10 mM MgCl2 at room temperature

 PEG cannot be used for precipitation of DNA fragments less than 150 bp in size, the reagent is ideally suited for removal of low-molecularweight DNA fragments such as those obtained on double digestion with restriction enzymes.

Washing twice with 70% ethanol by centrifugation for 5 min at room temperature was found to effectively remove the leftover PEG