Vitamin C serum sour

I have a L Ascorbic Acid serum that smells sour. it has been buffered properly and pH is 4.0-4.5. the colour has not changed, it is still colourless. I am wondering why has it gone sour. 


  • Sorry the pH is actually 4.5-5.0
  • You'll have to include the full formula (ingredients and amounts) to get more help here
  • MicroformulationMicroformulation Member, Professional Chemist
    You would have to include the whole Formula for any substantial help, but my guess is the L-Ascorbic Acid has oxidized. It can present as changes in color and/or odor. I would suggest using a more stable derivative. Microformulation Cosmetic Consulting provides Custom Formulations for both large Commercial accounts as well as smaller entrepreneurs. We can provide Naturally compliant Formulations under the NSF, NPA, Whole Foods and USDA Organic Certifications. BS.Pharm Albany College of Pharmacy, Union University.
Sign In or Register to comment.