Introduction -- Sunscreen Cosmetics: Advantages and Drawbacks -- Development of a Chromatographic Method to Estimate the In Vitro Percutaneous Absorption of Hydrosoluble UV Filters -- Determination of the Unconjugated Forms of Benzophenone-3 and Benzophenone-4 in Urine by Solid-Phase Extraction Coupled to a Liquid Chromatographic System with UV/VIS Detection by Using Autormated Sequential Injection Analysis -- Determination of Benzophenone-3 and Their Metabolites in Urine by Solid-Phase Extraction and Liquid Chromatography Tandem Mass Spectrometry -- Determination of Benzophenone-3 and Its Metabolites in Human Semen by Solid-Phase Extraction and Liquid Chromatography Tandem Mass Spectroscopy -- Eluciation of the In Vitro Biotransformation Products of Ethylhexyl Dimthyl PABA by Chromatographic Techniques Coupled to Mass Spectrometry -- Elucidation of the In Vivo Biotransformation Products of Ethylhexyl Dimethyl PABA By Liquid Chromatographic Techniques with Mass Spectrometry Detectors -- Determination of Ethylhexl Dimethyl PABA and Its Metabolites in Semen by Automated Solid-Phase Extraction and Liquid Chromatography Tandem Mass Spectrometry -- Determination of Methyl Benzylidene Camphor and Its Main Metabolite in Urine by Solid-Phase Extraction and Liquid Chromatography Tandem Mass Spectrometry -- Summary and General Conclusions.