Melatonin Solubility in Solvents

Regarding the difficulty in dissolving 2% Pure-Melatonin™ using Ethoxydiglycol (2.5%) and Propanediol (10%), according to the product information for Pure-Melatonin™, it is soluble in some oils and some glycols, including Ethoxydiglycol and 1,3-Propanediol.

The concentrations you used (Ethoxydiglycol 2.5%, Propanediol 10%) might be too low to fully dissolve Melatonin at a 2% concentration. The recommended usage rate for Pure-Melatonin™ is 0.1-3%, so 2% is within the suggested range.

To achieve full dissolution, you could try increasing the concentration of Ethoxydiglycol or Propanediol in your formulation. Alternatively, using a combination of suitable solvents might also improve solubility.

Experimenting with higher percentages of these solvents or trying a blend could help dissolve the 2% Pure-Melatonin™ completely.