I am investigating the antifungal activity of a oxindole derivative which is poorly water soluble. I am following the CLSI guidelines for broth dilution technique for dermatophytes. The compound dissolves in 100% DMSO, but when it diluted with water to 1%DMSO in the final solution, the compound get precipitated. I tried ethanol and Polyethylene glycol-400 1% as CLSI mentioned those as alternative cosolvents for poorly water-soluble antifungal agents. However, the outcome was same as 1% DMSO. Since pH should be around be around 7.4 during the test, changing pH is not possible. Please let me know any alternative solvent or any other solution.