Solution for Separation of Butylene Glycol and Vitamin C (L-Ascorbic Acid)

It is common to experience separation when mixing Butylene Glycol and L-ascorbic acid powder. This happens because L-ascorbic acid has limited solubility in Butylene Glycol. While Butylene Glycol can help disperse and stabilize L-ascorbic acid in water-free formulas, it is not a strong enough solvent on its own to keep higher concentrations of L-ascorbic acid fully dissolved over time, leading to the powder settling.

Here are some ways to address this separation issue:

1. Use a Co-solvent: Incorporating a co-solvent that improves the solubility of L-ascorbic acid is an effective method. Ethoxydiglycol is a popular choice for this purpose. It works well with glycols like Butylene Glycol and significantly enhances the dissolution and stability of L-ascorbic acid in the mixture.
2. Use a Suspending Agent: If you need to use a high concentration of Vitamin C or primarily use Butylene Glycol, adding a suspending agent can help. These agents increase the viscosity or create a light gel structure to keep the Vitamin C particles dispersed and prevent sedimentation.
3. Reduce Vitamin C Concentration: Lowering the concentration of L-ascorbic acid to a level that Butylene Glycol can fully dissolve or stably suspend can also solve the problem, though this might not be ideal if a high concentration is desired.

Based on your situation, using a co-solvent like Ethoxydiglycol is a recommended approach. Ethoxydiglycol acts as both a solvent and a carrier, improving the solubility of various substances, including L-ascorbic acid, and helping them stay dispersed in the formula. It is soluble in water, ethanol, and glycols like Butylene Glycol, making it suitable for your mixture.

Remember to check the recommended usage rate for Ethoxydiglycol in leave-on products, which is typically not more than 2.6% according to current regulations (please verify the latest regulations before use).