False-color image of the inhomogenous distribution of a sunscreen on the skin. The sunscreen is shown in red.

Characterization of sunscreens

Ex vivo determination of the protection efficiency of sunscreens in the UV, visible and IR spectral ranges of the sun radiation (determination of the universal sun protection factor USPF), analysis of the homogeneity of the distribution of sunscreen formulations on human skin under in vivo conditions (factor of inhomogeneity), optimization of the antioxidant content of cosmetic formulations, determination of the efficiency of the sunscreens against the formation of free radicals in human skin; determination of optical properties of sunscreens.

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Methods

Superimposed photographic image of the back of a person with topically applied sunscreen. The distribution of the sunscreen is shown superimposed by the fluorescence intensity.
Investigation of in vivo sunscreen distribution by fluorescence marker. Photo: H. Richter/Charité.

  • Tape stripping combined with spectroscopic measurements
  • In vivo laser scanning microscopy
  • In vivo and in vitro EPR spectroscopy
  • Integrating sphere UV-VIS-NIR-spectroscopy, Monte Carlo simulations
  • Resonance Raman spectroscopy
  • In vivo Raman micro-Spectroscopy
The diagram shows the  transmission of a sunscreen in % as a function of the wavelength in 280-320 nm (UVB) range and in the 320-400 nm (UVA) range. A lower transmission is reached in the UVB range. in the UVB and UVA spectral range.
Sum transmission of a sunscreen in the UVB and UVA spectral ranges. Photo: H. Richter/Charité.