My preference would be to use DMSO if the substance will dissolve in it. This is because DMSO is not volatile like ethanol, so you don't have to worry about the concentration of the stock solution increasing due to evaporation.

DMSO will give much better solubility than ethanol!

I think you could use water !?

The solution to your problem is simple: Seek and you shall find. You have identified two solvents for use. Why don't you test the hypothesis that there is no difference in the solubility of phenolic acids between ethanol and DMSO? You should have an answer at the end of experimentation. I think that will be better than going into this guessing game.

Thank you all for your suggestions.

Guobing Xiang As far as have read, rosmarinic acid is slightly soluble in water. As such, I think it is not going to dissolve completely if I use just water.

Hasib:

http://www.rosmarinicacid.com/

Depends on how high do you want your stock solution!

"

cientific Data on Rosmarinic Acid:

• Synonym: Ros A, [[3-(3,4-Dihydroxyphenyl)-1-oxo-2E-propenyl]oxy]-3,4-dihydroxy- benzenepropanoic acid.
• Chemical formula: C18H16O8
• Molecular Weight: 360.31 g/mol
• Soluble in water and organic solvents."

also

https://www.sciencedirect.com/science/article/abs/pii/S0167732216301477

"

Abstract

The solubility of rosmarinic acid was measured in water, ethanol, methanol, and in the binary solvent mixtures (ethanol + water) and (methanol + water), with different molar fraction values for ethanol and methanol, from (Xsolv = 0.10 to 0.90), over a temperature range of (T = 293.15, 298.15, 303.15, 308.2, 313.15 and 318.15) K. With increasing temperature and molar fraction of ethanol and methanol, the solubility of rosmarinic acid increased from 0.26 to 0.46 and from 0.28 to 0.49 respectively. The experimental solubility values were well correlated by the modified Apelblat equation. From the measured solubility data, the thermodynamic properties enthalpy of dissolution (ΔsolHRA) and entropy of dissolution ( ΔsolSRA) of rosmarinic acid, during the dissolution process in water, ethanol, methanol, and binary solvent mixtures (ethanol + water) and (methanol + water), could be calculated based on these fits. The results indicate that the dissolution process is endothermic."

Good luck!

Hello Hasib Ahmad

I think DMSO will do a good job in dissolving most of the compounds but please make sure that DMSO at whatever percentage you are using, doesn't have an inhibitory effect of its own.

To the best of my knowledge, above 10 percent DMSO is toxic to the fungal cells. But as Maurice Ekpenyong suggested, it is always best to go through experimental conclusion rather than guessing.

DMSO

One aspect often overlooked in such discussions is safety: DMSO can penetrate intact skin and take dissolved substances with it. If that substance is toxic, you have a problem that can only be reduced, but not solved, by wearing gloves. Thus, use DMSO only for substances of low toxicity (as rosmarinic acid)!

DMSQ should give a better result.