Importance of substrate roughness for in-vitro sun protection assessment / Louis Ferrero in IFSCC MAGAZINE, Vol. 9, N° 2 (04-05-06/2006)

[article]  inIFSCC MAGAZINE > Vol. 9, N° 2 (04-05-06/2006) . - p. 97-108 Titre : Importance of substrate roughness for in-vitro sun protection assessment Type de document : texte imprimé Auteurs : Louis Ferrero, Auteur ; Marc Pissavini, Auteur ; Adeline Dehais, Auteur ; Stephanie Marguerie, Auteur ; Leonhard Zastrow, Auteur Année de publication : 2006 Article en page(s) : p. 97-108 Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Sunscreen  testing'  'In  vitro  SPF'  'UVA  protection'  'Surface  roughness'  microtopography'  'Irregularfilm  geometry'  'UV  filters' Index. décimale : 668.5 Parfums et cosmétiques Résumé : The purpose of this study is to demonstrate the influence of plate roughness on well-known absolute or relative UV spectroscopic indices such as the in vitro SPF, in vitro UVA PF (PPD), UVA/UVB ratio, critical wavelength and SPF/UVA PF (PPD) ratio. First a roughness index was measured by non-contact surface topography analysis on different PMMA plates which are available today on the European market. A large difference between maximum and minimum plate roughness values could be measured ranging from 1.88 μm to 6.76 μm. Then the PMMA plates were grouped into five different roughness classes. To measure the different spectroscopic indices, the same sunscreen preparation was applied at the same amount rate (1 mg cm-2) to each of the selected plates. Large differences were noted for the absolute in vitro indices SPF and UVA PF (PPD), with the SPF varying in one instance from 13.5 to 40.7. On the other hand, the relative absorbance indices UVA/UVB ratio and critical wavelength showed a small but significant variation in relation to roughness. The SPF/UVA PF (PPD) ratio index based on direct in vitro values was found to be very sensitive to roughness variation. However, adjusting the UV absorbance curve to reach equality between the in vitro SPF and in vivo SPF is a recognized and efficient mathematical process to limit the variation. All these results can be interpreted using the irregular sunscreen film theory. Mathematical developments can be achieved by modeling the height distribution with a gamma function. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10847 [article]

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Photochemical behavior assessment of sunscreen preparations by in vitro UV spectroscopy / Louis Ferrero in IFSCC MAGAZINE, Vol. 7, N° 3 (07-08-09/2004)

[article]  inIFSCC MAGAZINE > Vol. 7, N° 3 (07-08-09/2004) . - p. 197-205 Titre : Photochemical behavior assessment of sunscreen preparations by in vitro UV spectroscopy Type de document : texte imprimé Auteurs : Louis Ferrero, Auteur ; Marc Pissavini, Auteur ; Stephanie Marguerie, Auteur ; Leonhard Zastrow, Auteur Année de publication : 2004 Article en page(s) : p. 197-205 Note générale : Bibliogr. Langues : Anglais (eng) Tags : 'Comportement  photochimique  in  vitre'  'Test  de  produit  antisolaire'  'Photoprotection  UVA  et  UVB  '  'Spectroscopie  UV' Index. décimale : 668.5 Parfums et cosmétiques Résumé : In this study, we used a spectroscopic method, found effective in measuring sunscreen photo-degradation results in terms of a photoabsorption decrease. The traditional approach was to measure variations in well-known parameters such as the absolute in vitro sun protection factor (SPF) or the relative UVA/UVB ratio after a controlled dose of UV radiation. However, these parameters fail to fully reflect the product's photochemical behavior. Variation in the SPF mainly depicts changes in UVB filtration, and variation in the relative parameter UVA/UVB ratio can be subjected to misinterpretation, as is the case for products in which a parallel loss of photoabsorption is observed in the UVA and UVB regions. In our laboratory, we developed a new approach using pure spectroscopic UVA and UVB attenuation factors called UVA attenuation factor and UVB attenuation factor. Attenuation factors are defined here as the inverse of the arithmetic mean of the transmittance data, taken either from the UVB region (290–320 nm, 1 nm steps) or the UVA region (320–400 nm, 1 nm steps). Using these two new spectroscopic indices, the photochemical behavior of a sunscreen formula can be assessed in each UV region. The general procedure consists of applying two UV doses to a film of sunscreen previously spread on a roughened polymethylmethacrylate plate and then measuring the UV transmission versus wavelength before and after the irradiation process. We tested different UV filters in a cosmetic base to demonstrate the efficacy of the method. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10475 [article]

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