title: UVA/UVB sunscreen determination by second-order derivative ultraviolet spectrophotometry.
abstract: UVA/UVB protective agents are important constituents in many cosmetics and sunscreen preparations. Analytical methodologies which enable the determination of combined substances with different spectrophotometric characteristics are therefore useful and cost-effective. To this end, the following substances in a sunscreen gel were analyzed: the UVB and UVA protective substances, 2-hydroxy-4-methoxy-benzophenone-5-sulphonic acid (BZP) and 2-phenylbenzymidazole-5-sulphonic acid (PBS), respectively, were evaluated by second-order derivative ultraviolet spectrophotometry in distinct solvents and wavelengths. The method used for determination of BZP in 95% ethanol was the zero-peak (ZP) at 356.0 nm. For PBS, the solvent used was 0.1 mol l-1 triethanolamine, and the methods were the ZP at 317.5 nm and the peak-peak (PP) at 317.5-323.0 nm. Statistical results for the methods showed linearity of 0.9999 and an average precision of 1.12% (ZP) for BZP, and 0.55% (ZP) and 0.63% (PP) for PBS. The average recovery for BZP and PBS were 97.28% (ZP), 103.13% (ZP) and 103.71% (PP), respectively.
authors.affiliation: Departamento de Produtos Farmacêuticos, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
authors.forename: J S
authors.initials: JS
authors.lastname: Azevedo
authors.forename: N S
authors.initials: NS
authors.lastname: Viana Junior
authors.forename: C D
authors.initials: CD
authors.lastname: Vianna Soares
mesh_terms: D001562:Benzimidazoles / Q000737:chemistry*; D001577:Benzophenones / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013451:Sulfonic Acids; D013473:Sunscreening Agents / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D001562:Benzimidazoles; D001577:Benzophenones; D013451:Sulfonic Acids; D013473:Sunscreening Agents; C009361:sulisobenzone; C499767:ensulizole