Direct determination of migration amount of fluorescent whitening agents in facial mask

Facial mask is a kind of skin care cosmetics, in which fluorescent whitening agents(FWAs) were added to make face skin look whiter and brighter. In this work, pig skin was used instead of human skin to test the methods. Three methods, including pig skin migration fluorescent spectrophotometry(FS), fiber paper migration FS, and fiber paper migration visual colourimetry(VC), were developed for determining the migration amount of FWAs from facial mask to pig skin. In the methods, a self-assembly light source and fluorescence collecting unit was used. The unit can be easily moved and the measurement was very convenient. Some experimental conditions were optimized. The fiber paper migration VC can give semi-quantitative results and was the simplest one in the three methods because collection, separation and detection of the fluorescence were not needed. Both the pig skin migration FS and fiber paper migration FS can give quantitative results and compared with fiber paper migration FS, the pig skin migration FS could give more practical results by simulating the real way of using facial mask. The limits of detection for disodium 4,4′-bis[(4-anilino-6-hydroxyethylamion-1,3,5-triazin-2-yl)amion]stilbene-2,2′-disulphonate(VBL) obtained by pig skin migration FS and fiber paper migration FS were 0.03 and 0.05 mg/m2, respectively. 96 kinds of samples were analyzed and the migration amounts of FWAs in 21 kinds of samples were detectable. Correlations between migration amounts obtained by the three methods were very good. Experimental results indicate that the present methods can be applied to the determination of migration amount of FWAs in facial masks.