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Titanium dioxide determination in sunscreen by energy dispersive X-ray fluorescence methodology

2008; Elsevier BV; Volume: 613; Issue: 2 Linguagem: Inglês

10.1016/j.aca.2008.02.058

1873-4324

Fábio Luiz Melquíades, Diego de Dio Ferreira, Carlos Roberto Appoloni, Fábio Lopes, Audrey Alesandra Stinghen Garcia Lonni, Fabiana Oliveira, José Carlos Duarte,

melanin and skin pigmentation

Nowadays there are many sun-protection cosmetics incorporating chemical and/or physical UV filters as active ingredients and there are no official methods to determine these kinds of compounds in sunscreen cosmetics. The objective of this work is to estimate TiO(2) concentration, without sample preparation, employing a portable energy dispersive X-ray fluorescence (EDXRF), aiming to estimate the sun protection factor (SPF) due to the physical barrier in sunscreen composition, and also identify the metals present in the samples. A portable EDXRF system was used for the analysis of fifteen commercial samples. It was also prepared three formulations estimated in FPS-30 using TiO(2) at 5%. Quantification was performed using calibration curves with standards from 1 to 30%. The physical barrier contribution in the SPF, associated to Ti concentration, was determined for all samples. The presence of some elements, like K, Zn, Br and Sr was detected in the sunscreen, identifying chemical elements that were not cited in the formulations. Three commercial samples were analyzed for total SPF determination and the result shows that the measured value is 10% lower than the nominal one.