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Copyright @ Pol J Cosmetol
Pol J Cosmetol 2021, 24(3): 143-154pl,en  Methods of determining lipophilicityJacek Arct 1/, Ewa Starzyk 2/, Andrzej Jończyk 3/ 1/ Dr Seidel´s Foundation, Warsaw 2/ Polish Union of the Cosmetics Industry 3/ Faculty of Chemistry, Warsaw University of Technology Summary Lipophilicity is a value determines the ability of a cosmetically active substance to penetrate the skin, which, in addition to biological activity, determines the suitability of the compound. Therefore, many different methods of measuring lipophilicity, both experimental and theoretical, have been developed. The practical techniques come down to the most precise determination of the compound´s coefficient between two phases, aqueous and organic. Direct measurement is cumbersome and challenging to automate. Therefore, several chromatographic methods have been developed. Most of these methods are based on the separation of substances between the mobile and stationary phases with the applied second liquid phase. The determined Rf values are converted into the respective partition coefficients. In addition to experimental methods, there are many mathematical methods, both semi-empirical ones based on experimental results and entirely computational ones based on descriptors of individual parts of the molecule. The latter has become very popular, and they allow the determination of the values of the partition coefficients directly by computer methods. The calculated values differ slightly from the extreme ones, are usually marginally lower but allow for an approximate determination of lipophilicity, generally sufficient to determine the cosmetic suitability of the substance. Key words: lipophilicity, partition coefficient, logP, chromatographic methods, calculation of l-profile, descriptors |