How much % vitamin C is in the serum?

In our serum we used a stable form of vitamin C – ascorbyl tetraisopalmitate, which does not degrade quickly and the addition of already a small amount (less than 1%) works effectively. Most often, cosmetics with very high concentrations of vitamin C use ascorbic acid, which is the most unstable form of this vitamin. In a very short time its activity decreases and the cosmetic no longer works as it should. For this reason, there is no need to use a stable form of vitamin C in such high concentrations as ascorbic acid.