Determination of Urea and Allantoin in Cosmetics
Urea and allantoin are added to cosmetic products for skin protection and regeneration, especially for the treatment of dry skin, and analyzed for QC purposes. As polar compounds, they are not ideal for reversed-phase HPLC separations. Neutral hydrophilic compounds like urea and allantoin are best analyzed by hydrophilic interaction chromatography (HILIC). Traditional HILIC columns use silica modified with a hydrophilic group such as diol or cyano. Analytes are adsorbed and subsequently eluted with mobile phases containing high percentages of organic solvent (>75%).