Mentioned extensively in peer-reviewed scientific journals, C E Ferulic is a vitamin C serum demonstrated to provide powerful environmental protection due to a synergistic combination of 15% pure vitamin C (l-ascorbic acid), pure vitamin E (alpha-tocopherol) and 0.5% ferulic acid. It is formulated under the Duke Antioxidant patent. Vitamin C is a highly-potent antioxidant that by its structure has difficultly being effectively absorbed by skin. The Duke Antioxidant patent outlines the formulation parameters required for effective delivery of vitamin C to skin: 1) pure l-ascorbic acid (vitamin C); 2) an acidic pH within the 2.0-3.5 pH range and; 3) a concentration between 10%-20%. SkinCeuticals is the only brand to formulate antioxidants according to these parameters.