Water retention of treated stratum corneum measured by a coupling method: thermal desorption-mass spectrometry

A thermal desorption autosampler coupled to a mass spectrometer has been used to measure the in vitro water retention of human stratum corneum as a function of treatment applied. Samples were treated with ingredients possessing good hygroscopic properties which are used in the formulation of moisturizing creams. After being treated, stratum corneum samples were dried and rehydrated and then analysed. The paper describes the method used to quantify their hygroscopic capacity in terms of the percentage of water retained. Ten humectants were examined, of which urea, glycerine, ammonium lactate and a new salt of an α-hydroxy acid were found to have the highest activities. This method can also be used to quantify the water retention capacity of various types of pathological skin such as ichthyosis and psoriasis.