Abstract. From a data bank of 2467 odoriferous products, the similarities between 74 notes used in perfumery were calculated. The similarity matrix (74,74) contains -63% of zero values and shows that only a few pairs of notes present high similarity coefficients. A fine analysis using ascending hierarchical taxonomy with the complete linkage procedure shows that 14 notes are isolated while 60 notes are regrouped in 27 groups containing two to four notes. The isolated notes correspond to well-defined structural particularities. Some pairs of notes or groups present similarities in their chemical structures but some groups are built on the basis of semantic processes. This study shows that the notes are generally independent, with no strict hierarchy among them, and rules out the existence of primary odors.

Abstract. In order to analyze the relationships among 32 descriptors of odors (notes), similarity coefficients were calculated using a data bank of 628 odoriferous products. The simple examination of the similarity matrix (32,32) has shown notes selectively and strongly associated (e.g. camphoraceous -pincy and musky-powdery) and others less selectively associated (e.g. floral, green and herbaceous). This analysis was completed by four multivariate statistical methods. Non-linear mapping (NLM) proved to be more efficient than principal coordinates analysis for planar representation of olfactory notes, and has given results similar to those previously obtained using other data and other methods (similar disposition of notes around the central note 'floral'). Furthermore, the ascending hierarchical taxonomy and the minimal spanning tree were coherent with the NLM representation. These three methods complete each other and constitute a convenient system to analyze odor descriptions.

Synopsis Diffusion of perfume ingredients from skin or hair is measured using an original method based on dynamic headspace technology. This has been used for pure odorants, fine fragrances, as well as for perfumed cosmetic applications such as soaps, creams or shampoos, in order to characterize diffusion processes and air/skin or air/hair partitioning. Accordingly, a special collection system, applied on the inner face of the forearm, has been developed, allowing the adsorption of diffusing organic vapours from skin onto Tenax (poly-diphenyl phenylene oxide) with a controlled air flow rate. A simple model composition containing eleven volatile synthetic odorants was prepared in an alcoholic matrix and the solution was applied onto the skin. The diffusion rate of the different components was measured by determining the concentration of each in the gas phase versus time. Conversely, the same experiment was effected by the application of an alcoholic solution of each individual component. In this manner, the relative diffusion from skin of the components alone or mixed was compared using the same experimental technique. The effect of a musky component was also tested. Both compositions (with and without musk) were then applied in a soap base. Thus, following a rigorous protocol, the forearm was washed with the perfumed soap and rinsed with water before collection of the headspace. The results show the different diffusion rates of the individual odorants. In particular, components evaporate slower from the skin when they have been applied from a soap bar compared to when they have been applied from alcoholic solution. We also present results describing the characterization of skin types using a panel comprised of 80 people (40 females and 40 males); amount of sebum, hydration and pH were systematically measured on different parts of the face, the neck as well as the outer and inner faces of the forearm. The panelists were then classified into different sub-groups taking into account these parameters. It should be noted that the foregoing results were obtained on an 'average'skin type.