UV–vis spectra were carried out in the supernatant of both vitamins@P25TiO₂NPs samples after centrifugation to measure the amount of unbound vitamin. Standard curves at 375 nm and 255 nm were done for vitamin B2 and C, respectively, using a Synergy BioTeK multi-mode microplate reader.

There are many uses of titanium dioxide that we don't know about because they were made exempt from being on the package in 1977, said Faber, who added that nothing much has changed since – other than the FDA approving some other uses of the color additive, such as expanding the use of mica-based pearlescent pigments (prepared from titanium dioxide) as color additives in distilled spirits over recent years.