I have a researcher that needs their 0.5X E2 embryo media to become an isotonic solution of 270mOsmol, which is similar to the interstitial fluid of zebrafish. She has found literature that shows that they use 135mM of either NaCl, sucrose, or sorbitol (d-sorbitol is what we have in the lab).

I was curious on if it would be better to add it as a solid or make the 135mM solution of each. My concern of making solutions to add would change the concentration of the E2. or would I need to adjust the amount of salts in the protocol of the 0.5X E2 to make it the desired mM to get the correct osmolarity?

I'm really struggling on how to go about this, so if anyone has any suggestions, that would be great! Thanks!