Formulation with Propanediol or Butylene Glycol as Base for Vitamin C

Regarding your questions about using Propanediol or Butylene Glycol as the main base for dissolving L-ascorbic acid Vitamin C without distilled water, and the effect of high concentrations on absorption:

1. Using Glycols as the Main Base: Yes, it is practically possible and often done to use glycols like Propanediol or Butylene Glycol as the main base for dissolving L-ascorbic acid, omitting distilled water. L-ascorbic acid is prone to oxidation and degradation in water-based solutions. Using anhydrous (water-free) bases like glycols or silicones can significantly improve the stability of L-ascorbic acid. The descriptions for L-ascorbic acid grades (such as Vitamin C (L-ascorbic acid) (Ultra-Fine)) mention suitability for anhydrous formulas.

2. Effect of High Concentrations on Absorption: Propanediol and Butylene Glycol act as solvents and humectants. While they can help dissolve active ingredients like Vitamin C and may enhance their penetration into the skin, simply using very high percentages doesn't necessarily guarantee significantly increased absorption and can lead to undesirable formulation properties such as stickiness or potential skin irritation, especially at concentrations exceeding recommended usage rates (typically up to 20%, although Butylene Glycol can be used up to 50% in some cases). Their primary role is as a stable solvent for L-ascorbic acid in anhydrous formulations and providing a pleasant skin feel and moisturization.

In summary, using Propanediol or Butylene Glycol as the primary base without water is a valid approach for stabilizing L-ascorbic acid. While these glycols can aid absorption, their concentration should be balanced for efficacy, stability, and user comfort.