I just recently conducted an experiment in my biochemistry class where we had to add DNA to distilled water, isotonic saline and 2.5M NaCl. I noticed different physical aspects depending on the solvent, but I'm not sure how I would categorize them. Here's what I saw:

  • Distilled: fibrous precipitate, cloudy liquid
  • Isotonic: Honestly barely noticed a change here? Maybe I wasn't looking hard enough
  • 2.5M: salt precipitate at the bottom and fibres

I know DNA is polar so solubility should increase as the polarity of the solvent increases. But to my recollection what I saw in 2.5M saline vs distilled water did not differ much. However, there is always the possibility that I could have made some experimental errors that led to inaccurate observations.

So, can someone help me deduce the solubility of DNA (simply soluble/not soluble) in each of these solvents, or refer me to a paper I can read? Thanks in advance!

  • $\begingroup$ Do you have any pictures that might help us gauge exactly what you saw? Here is a related Q&A on DNA solubility in water $\endgroup$ – James Mar 19 '18 at 17:46
  • $\begingroup$ imgur.com/a/Apbps this is what I saw when I added distilled water to the 2.5M NaCl (final conc of 0.16M), but other than that no photos! And I will refer to that discussion for water, thank you :) $\endgroup$ – ro_the_electron Mar 20 '18 at 20:29

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