10 JOURNAL OF COSMETIC SCIENCE Methylen bis benzotriazoyl tetramethylbutylphenol, the new broadbrand UV filter ac- cepted in the EU has a distribution profile different from those of classical UV filters in the uppermost part of the stratum corneum that may change its performance as a filter (increased resistance to water, to rubbing?). This method has demonstrated that among the filters studied some are not degraded under UV exposure while others (such as octyl methoxycinnamate) show chemical transformation (new product detected by HPLC), which in this case doesn't change their activity. This method could be a good candidate to replace the current method of assessing photostability on quartz plates because it takes into account product interac- tions with the stratum corneum. REFERENCES (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) H. U. Gonzenbach and G. H. Pittet, Photostability, a Must? (Roche Vitamins and Fine Chemicals, Neuilly-sur-Seine, France, 1998). J. Meijer and M. Loden, Stability analysis of three UV-filters using HPLC, J. Chromatogr., 18, 1821-1832 0995). J.E. Dinunzio and R. Rao Gadde, Determination of sunscreen compounds in topical sunscreen products,J. Chromatogr., 519, 177-124 (1990). S.C. Rastogi and G. H. Jensen, Identification of UV filters in sunscreen products by high-performance liquid chromatography-diode array detection, J. Chromatogr., 828, 311-316 (1998). V. Vanquerp, C. Rodriguez, C. Coiffard, L.J.M. Coiffard, and Y. De Roeck-Holtzhauer, High performance liquid chromatography method for the comparison of the photostability of five sunscreen agents,J. Chromatogr., 832, 273-277 (1999). R. Schwarzenbach and L. Bertschi, Determination of photostability in diluted solutions, IFSCC-- Between Congress Conference: Facts and Illusions in Cosmetics, Montreux, Switzerland, September 1995, poster 16, pp. 277-282. A. Deftandre and G. Lang, Photostability assessment of sunscreens: Benzylidene camphor and diben- zoylmethane derivatives, Int. J. Cosmet. Sci., 10, 53-62 (1988). G. Marginean Lazar, A. E. Fructus, A. Baillet, J. L. Bocquet, P. Thomas, and J.P. Marty, Sunscreens' photochemical behaviour: In vivo evaluation by the stripping method, Int. J. Cosmet. Sci., 19, 87-101 (1997). I. Beck, A. Deftandre, G. Lang, R. Arnaud, and J. Lemaire, Study of the photochemical behaviour of sunscreens--Benzylidene camphor and derivatives, Int. J. Cosmet. Sci., 3, 139 (1981). I. Beck, A. Deftandre, G. Lang, R. Arnaud, and J. Lemaire, Study of the photochemical behaviour of sunscreens--Benzylidene camphor and derivatives. II. Photosensitized isomerization by aromatic ke- tones and deactivation of the 8-methoxypsoralen triplet state, J. Photochem., 30, 215-227 (1985). P. Morliere, T. Sa. E. Melo, L. Dubertret, M. Giraud, and R. Santos, A study of the photochemical properties of some cinnamate sunscreens by steady state and laser flash photolysis, Photochem. Photobid., 36, 395-399 (1982). B.L. Diffey, R. P. Stokes, S. Forestier, C. Mazilier, A. Richard, and A. Rougier, Suncare product photostability: A key parameter for a more realistic in vitro efficacy evaluation. Part I. In vitro efficacy assessment. Protection of the Skin Against Ultraviolet Radiations, 137-142 0998). S. Forestier, C. Mazilier, A. Richard, and A. Rougier, Suncare product photostability: A key parameter for a more realistic in vitro efficacy evaluation. Part II. Chromatographic analysis, Protection of the Skin Agaimt Ultraviolet Radiatiom, 143-147 (1998). A. Karomeyer, W. Westerhof, P. A. Bolhuis, A.J. Ris, and E. A. Hische, The spectral stability of several sunscreening agents on stratum corneum sheets, Int. J. Cosmet. Sci., 9, 125-136 (1987). G. Marginean Lazar, A. Baillet, A. E. Fructus, S. Togkoz, C. M. Vincent, and J.P. Marty, Evaluation of percutaneous absorption and photochemical behaviour of sunscreens by stripping, Twentieth Congress of the International Federation of the Societies of Cosmetic Chemists, September 14-18, 1998, pp. 105-114. G. Marginean Lazar, A. Baillet, A.E. Fructus, J. Arnaud-Battandier, D. Ferrier, and J.P. Marty,

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