Abstract: Formulated systems are complex matrices with many ingredients, often incompatible, and likely to interact. To avoid a long and tedious traditional trial and error approach, it seems appropriate to have robust experimental and theoretical tools which will help in understanding and rationalizing the behavior of some components in order to be able, in fine, to establish relationships between chemical structures, physicochemical properties and functional properties. The CÏSCO research group of the University of Lille has been developing and using new experimental methods for several years. We will illustrate, through concrete examples, the method that we named "PIT-slope" (Figure 1) which is particularly robust for surfactants and additives to quantify their amphiphilicity and the EACN (Equivalent Alkane Carbon Number) which provides a useful classification of perfumes and complex oils.