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Abstrait

Determination Of Sun Protection Factor By Uv-Vis Spectrophotometry

Rafaelaa Nobre and Ana Paulaa Fonseca

Background: Sunscreen products contain active ingredients that can absorb, reflect or scatter the sunlight, depending on their nature. We can evaluate the effectiveness of a sunscreen by determining the sun protection factor (SPF). This SPF should be specific for each phototype, so as to the protection against the damaging effects of UV rays may be the best. Besides the choice of the adequate sunscreen, care must be taken with the application method and the amount of product that is applied. In most cases, the real SPF did not correspond to the labeled SPF.
Aim: The aim of this study was to determine the real SPF values of ten chemical or physical sunscreens through UV-Visible Spectroscopy, as well as the degradation by direct solar radiation and temperature at 37°C.
Methods: UV-Vis spectrophotometry was used to measure the UV absorption of each sample and the Mansur equation was applied to obtain the final SPF.
Results: The majority of the studied sunscreens have much lower SPF when compared to the labeled value.
Conclusion: To avoid the damaging effects of UV radiation, we have to encourage the correct use of sunscreen, reapplication and double-application to reach a desirable effect of the sunscreen, promote the use of other physical protection (clothes, hats) and avoid the hours of peak radiation. We also concluded that it is important to have constant monitoring of SPF on sunscreens marketed in World, in order to allow their use with complete quality assurance.