Multi-element analysis of sunscreens using slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

Abstract

The determination of Cu, As, Cd, Sb, Hg, Pb and Bi in titanium based sunscreens by ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) is described. Thioacetamide (TAC) was used as the modifier to enhance the volatility of the elements studied. The influence of the instrument operating conditions and slurry preparation on the ion signals were studied. A relatively low vaporization temperature of 1500 °C was used, which separated the analytes from the major matrix component, titanium, thus improved the ion signals. The method has been applied to determine Cu, As, Cd, Sb, Hg, Pb and Bi in a reference material GBW09305 cosmetic (cream), and three brands of titanium based sunscreens using isotope dilution and standard addition calibration methods. The concentrations obtained are in good agreement between the different calibration methods. The results of As and Pb in the reference material agreed with the certified values. The precision between the sample replicates was better than 9%, when the USS-ETV-ICP-MS technique was used. The method detection limits estimated from standard addition curves were 0.8, 0.4, 0.2, 0.4, 0.8, 0.5 and 0.1 ng g⁻¹ for Cu, As, Cd, Sb, Hg, Pb and Bi, respectively, in real titanium based sunscreens.