# Dissolving in DMSO semantics

What does it mean when a substance (powder) is 'dissolved in DMSO and used at $\mathrm{5~\%}$'

Does is mean that the substance is first dissolved in DMSO and then added to another solution where it makes up $\mathrm{5~\%}$ of that total solution? Or does it mean something else?

• When adding a solute to a solvent the only way that a "5% solution" makes sense is by weight percent. When mixing two liquids it could mean "volume percent" (vol. %) or "weight percent" (wt. %) so the writer should specify which is intended.
– MaxW
Dec 31 '15 at 15:21
• See my comment on the answer below Jan 3 '16 at 14:32

A good author should express whether percents are weight $(wt./wt.)$, volume ($vl./vl.$) or weight/volume ($wt./vl.$). This unfortunately does not happen often. Typically for solids dissolved in liquids the percent is weight/volume given as : $$\frac{weight}{volume}$$ and expressed as: $$5\% (wt./vl.)$$