I know that vitamin C degrades over time (as I understand through oxidation). However, I am having trouble understanding how changing the pH of the solution in which the vitamin C is affects the rate at which the vitamin C degrades.

Among others, Roig et al. [1] demonstrated that there is indeed a change in degradation based on pH.


  1. Roig, M. G.; Rivera, Z. S.; Kennedy, J. F. A Model Study on Rate of Degradation of L-Ascorbic Acid during Processing Using Home-Produced Juice Concentrates. International Journal of Food Sciences and Nutrition 1995, 46 (2), 107–115. https://doi.org/10/fgwc5c.

Ascorbic Acid is a known antioxidant molecule and its stability has always been an issue especially for pharma industry which often makes use of AA in formulation. Now as much as pH is a culprit in AA degradation, its only one among other factors like solvent, exposure to light/uv, and the nature of solution (viscous/non-viscous). There are quite a lot of studies on stability of Ascorbic Acid like this one

I normally prepare Ascorbic Acid freshly for each experiment, but it would be an interesting experiment to check the stability of AA for an extended time period at different pH values.

Here is an interesting simulation demonstrating degradation of Ascorbic Acid.

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    $\begingroup$ Thank you for your answer, and welcome to the site! Are you sure your answer addresses the question's fundamental inquiry (How is AA degradation affected by pH)? $\endgroup$ – William R. Ebenezer Jul 17 at 8:36

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