The 15% concentration of liquid L-ascorbic acid in this decades-old formula is particularly effective and well studied. That may explain the exorbitant price.

For example, L-ascorbic acid, a form of vitamin C found in many skin care products, degrades when it is exposed to heat, a high pH or sunlight, she said — which can happen during transit and ...

American Chemical Society: Chemistry for Life.L -Ascorbic acid, more familiarly known as vitamin C, is widely found in nature. It is particularly abundant in citrus and stone fruits, berries ...