Journal of the Brazilian Chemical Society
Print version ISSN 0103-5053
SCHWAB, Nicolas V.; DA-COL, José Augusto; TERRA, Juliana and BUENO, Maria Izabel M. S.. Fast direct determination of titanium dioxide in toothpastes by X-Ray fluorescence and multivariate calibration. J. Braz. Chem. Soc. [online]. 2012, vol.23, n.3, pp. 546-554. ISSN 0103-5053. http://dx.doi.org/10.1590/S0103-50532012000300023.
Recently, the International Agency for Research on Cancer (IARC) has classified titanium dioxide as potentially carcinogenic. Titanium dioxide is a pigment generally used as opacifying agent in toothpastes, but there is no indication of the percentage of this oxide in these products. In this work, 22 distinct toothpaste samples were calcinated at 800 °C and TiO2 concentration was determined with energy dispersive X-Ray fluorescence (EDXRF) via fundamental parameter (FP) method. The same samples were irradiated in natura for 100 s and through the correlation of spectra and concentrations formerly determined, a multivariate calibration model was constructed. Eight latent variables described the partial least square regression (PLS) model with average errors of 9.5%, indicating that beyond the peak of titanium, the information of the X-Ray scattering irradiation is also important to minimize errors when using an univariate calibration. As a major advantage, the method allows analysis without pretreatment of the samples, with a throughput of 24 determinations per hour.
Keywords : toothpaste; titanium dioxide; X-ray fluorescence; partial least square regression; chemometrics.