Determination of Pb, As in Liquid Cosmetics and Cl in Bath Salts by X-Ray Fluorescence Spectrometry

The focusing X-ray fluorescence spectrometer was used to determine Pb and As in liquid cosmetics and Cl^- in bath salt, and a new method of sample introduction-film mounted sample bottle method was proposed. Liquid samples could be introduced directly for analysis, but for solid sample, e.g. bath salt, it should be ignited, ashed and dissolved in water by the mass ratio of 1 to 5, and the solution was then used for analysis. As described in the method, small bottles having its volume of 2 mL, keeping the deviation of height of its bottle mouth within 0.2 mm and attached with holed caps were selected for use as sample introduction bottles (abbre. as SIB). Liquid sample (or solution) was transferred into the SIB with the liquid surface a little higher over the bottle mouth. A piece of 2.5 μm Mylar film was mounted on the liquid sample, and the cap was screwed on, keeping the Mylar film to adhere tightly to the liquid surface and to be level and smooth. The SIB was then moved onto the sample tab and focused with laser. The extended Compton scattering model was used for matrix correction and fitting of calibration curve. As shown by the results, RSD (n=11) of the major contents of chlorine was 0.65%. RSDs (n=11) for traces of Pb, As were both less than 5.0%, and detection limits for Pb and As were 3.0, 1.0 mg·L^-1, respectively. The results obtained by this method were consistent with those found by the standard method.