In vitro comparison between two products (ageing, batch, benchmark, etc.)

The statistical comparison method is used to compare two sunscreen products in terms of ageing, batch, benchmarck, etc. Based on all absorbance spectrum checking between a reference and a product to be tested by means of an in vitro method, two important rules are followed. First, compare at the same time and same conditions the two products to limit the measurements variability. Second, a three stepped checking based on the absorbance values including comparison of the shape of the curves, variability and intensity.