[Ryukk9]

Hello, Im trying to find a way to properly dissolve melatonin in vegetable glycerin whereas melatonin is dissolving really bad in it. Has anyone some experience with this process ? I´ll be glad for any advice.

[Corribus]

Speaking from the standpoint of chemistry with no implications intended for actual product development:

First, you need to specify what concentration of solution you are trying to obtain. Everything is soluble in everything to some degree - the question is how much.

Beyond that, the solubility is the solubility - you can't magically make something more soluble just by wishing it so. You can increase solubility by changing the environmental conditions (e.g., heating). You can use a surfactant, which mediates the interactions between the solute and the solvent. Or you can chemically modify the solute so that the solubility is higher - but in that case you may change other properties of the solute as well.

Bear in mind that while solubility is a thermodynamic property, there is a kinetic component as well. The thermodynamic solubility may be higher than what you observe when trying to get something to dissolve simply by adding it to a solvent. You can speed up the dissolution processes by breaking up a solid before adding it using mechanical force (grinding in a mortar and pestle, say) or by applying sheer force to the suspension (sonication). Keep in mind that at very high applied energy, chemical changes to the solute are possible. Heat/cool cycles can also be used to speed up a sluggish dissolution.