What is the percentage of Vitamin C in your Brighten Up Vitamin C Serum?

We formulated our Vitamin C Serum with ascorbic acid polypeptide, a version of Vitamin C that retains its potency far longer than traditional formulas. The typical 10-20% concentration is based on L-Ascorbic acid, which can be problematic because it requires a high concentration but degrades almost immediately. The new Vitamin C derivative that we use, ascorbic acid polypeptide, is more potent so it is used in smaller doses and is way more shelf stable. It's in there at a concentration of 1.5% (the maximum dose for this ingredient is 2.0%). We decided to go just slightly below that maximum to avoid any unnecessary irritation without sacrificing efficacy.