“…The analysis of cosmetics represents a challenge mainly because of the great variety of ingredients and formulations leading to immense matrix complexity and variability. In this field, many analytical techniques play a crucial role, each designed to meet specific demands to understand the molecular nature of cosmetic products and the complexity of their formulations: chromatography (liquid chromatography (LC) [ 5 , 6 ], gas chromatography (GC) [ 7 , 8 ], supercritical fluid chromatography (SFC) [ 9 ], capillary electrophoresis (CE) [ 10 , 11 ], spectroscopy [ 12 , 13 , 14 , 15 , 16 , 17 ], electrochemistry [ 18 ], colorimetry [ 19 , 20 ], mass spectrometry (MS) [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ], interfacial methods [ 32 , 33 ], rheological assessment [ 34 , 35 , 36 ], olfactometry, and electronic nose technology [ 37 , 38 , 39 ]. Recent advances in MS and ionization techniques provide access to richer and deeper information on monitoring the molecular compositions of endogenous or exogenous compounds in or on the skin as well as those used in cosmetic formulations, with less time and effort.…”