On the applicability and performance of the single particle ICP-MS nano-dispersion characterization method in cases complicated by spectral interferences

Abstract

In the present study, the applicability of single particle inductively coupled plasma mass spectroscopy (SP-ICP-MS) to the characterization of nano-dispersions is investigated in cases when the measurements are complicated by isobaric or polyatomic interferences. The specific classes of problems associated with spectral interferences in SP-ICP-MS measurements are described and the ways potentially applicable to the mitigation of these are discussed. Detailed experimental data are presented for the dispersions of Fe₂O₃, Cr₂O₃ and ZnO nanoparticles (NPs) stabilized with polyacrylic acid. The analytical performance of helium collision cell SP-ICP-MS was also assessed in detail. Although the sensitivity of the measurement for medium or low mass analytes decreased when the collision cell was used, the repeatability of the signal remained surprisingly good (3–6% RSD) even when NP signals were less than 50 counts and the acquisition time was kept as low as 100 s. In the helium mode, the size detection limit values were found to be 39 nm for Cr₂O₃, 15 nm for Fe₂O₃, 20 nm for ZnO and 35 nm for Ag NPs. These values are only 10–15% larger than comparable values found in no gas mode.