Quantification of the toxic metals in microplastics from seawater and beach sediments by SF-ICP-MS: comparison of different sample preparation methods

The sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) technique was applied to the determination of toxic metals in microplastics (MPs) occurring in seawater and beach sediments from the Caspian Sea. The abundance of MPs in seawater was 86.4 ± 13.2 items/m³, while in coastal sediments, amounted at 147.1 ± 7.9 items/kg. Thirteen metals were then chosen: Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sb, Sn, Ti, V and Zn, which pose global risks to marine environment and can originate from multiple anthropogenic sources. Three sample preparation techniques were compared for determining metal concentrations on MPs isolated from seawater and coastal sediments of the Caspian Sea. The accuracy of SF-ICP-MS measurements was proved by analysing certified reference materials, IAEA-158 marine sediment and CASS-6 (seawater). The mean repeatability of the method (RSD) was 1–4%, and intermediate precision was averaging 4–7% for all metals. The trueness, calculated from deviations from the independently asserted values as a relative error do not exceed 14%.