Yesterday and today I made a salt saturated DMSO solution for coral DNA preservation in the field. I found support for this solution as a preservative for corals based on Gaither et al. 2011 and Concepcion et al. 2014. There is also an older article by Seutin et al. 1991 that appears to have initially promoted this solution for animal DNA preservation.

On the web I found this protocol for making salt saturated DMSO, and this is what I followed.

First I made 1L 0.5M EDTA:

900 ml nanopure H20
EDTA (FW 292.24) 146.12 g
NaOH pellets to pH EDTA to 8.0
Brought final volume to 1L

I ended up adding LOTS of NaOH pellets to bring the pH up since I did not have disodium EDTA. This took a few hours.

Then for the salt saturated DMSO:

0.5M disodium EDTA 1L
Dimethyl Sulfoxide (DMSO) 400mL
Nanopure water 500mL
NaCl – Enough to saturate the solution.

First I added 300 g NaCl, then another 100 g , then another 20 g. I brought the volume up to 2 L with nanopure water. Some solid NaCl remained, which was left out when I transferred the solution to a container. I then autoclaved the solution.