I am trying to make 250 mM Aspartame (CAS RN: 22839-47-0) and used autoclaved dist. water as solvent. But after trying with water , cell culture grade ethanol and DMSO with different concentrations it is not getting soluble at all. Finally I could make the aspartame soluble at concentration of 25mM which is 10 times lower than the concentration I need. In some literatures they have used concentrations like 1M even dissolved in DMEM (Ref. Pandurangan, Muthuraman, Gansukh Enkhtaivan, and Doo Hwan Kim. "Cytotoxic effects of aspartame on human cervical carcinoma cells." Toxicology Research 5.1 (2016): 45-52). Can anyone help me in resolving this problem?