Formulation Discoloration: Identifying the Cause

Based on the ingredients you provided (Vitamin B3, Wrinkle Lax, Glutathione, Hyaluronic Acid (Standard Molecule), Apple Stem Cell, Pro Polymer, DI Water), the most probable cause for the yellowing of your formulation over time (3-4 months) is Glutathione.

Glutathione, especially in its reduced form, is known to be susceptible to oxidation. This process can lead to the degradation of the compound and result in a yellow or brownish discoloration in the product, particularly when exposed to air, light, or heat over time.

While Vitamin B3 (Niacinamide) can sometimes contribute to discoloration under specific conditions or in reactions with other ingredients, Glutathione is a more common and significant factor for the type of yellowing you are observing due to its inherent instability towards oxidation.

Other ingredients like Hyaluronic Acid, Apple Stem Cell Extract, and Pro Polymer are generally stable and less likely to cause this type of discoloration on their own. DI Water is the solvent and does not cause discoloration. Wrinkle Lax is likely a peptide-based ingredient, and while peptide stability can vary, the strong yellowing is most typically linked to Glutathione oxidation.

To help minimize or slow down this yellowing process in formulations containing Glutathione, consider the following:

• Storage: Store the product in a cool, dark place, away from direct sunlight and high temperatures.
• Packaging: Use packaging that protects the product from light and air, such as opaque bottles or airless pumps.
• Antioxidants: Incorporating additional antioxidants into the formulation may help to stabilize Glutathione and inhibit its oxidation.
• pH Level: Ensure the formulation's pH is optimized for the stability of all ingredients, especially Glutathione.
• Ingredient Quality: The purity and quality of the raw materials used can significantly impact the stability of the final product.

Here are some of the relevant products found based on your ingredient list:

• Glutathione (L-Glutathione Reduced)
• Glutathione (L-Glutathione) (Extrasol)
• L-Glutathione Liquid (Deodorized, Colorless)
• Safe-B3™ (Vitamin B3, Niacinamide)
• Safe-B3™ (Vitamin B3, Niacinamide, Switzerland)
• Extreme-B3™ (Vitamin B3, Niacinamide, Highest Purity)
• Hyaluronic Acid (Standard Molecule)
• Apple Stem Cell Extract (AppleCell™ Powder)
• Pro Polymer™ (Gel Maker)
• Pro Polymer™ Silk
• Wrinkle-Lax™ คลายริ้วรอย

In conclusion, the yellowing observed in your formulation after 3-4 months is most likely caused by the oxidation of Glutathione.