Single particle inductively coupled plasma mass spectrometry with and without flow injection for the characterization of nickel nanoparticles

Abstract

This work compares the performance of transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), single particle inductively coupled plasma mass spectrometry (spICPMS) and flow injection (FI) coupled to spICPMS for the characterization of synthetic ferromagnetic Ni nanoparticles (NPs) prepared with and without polyvinylpyrrolidone (PVP) stabilizer. Whereas single NPs measurement by XRD yielded nominal diameters of 13.7 and 16.6 nm with and without PVP respectively, a diameter of 100–130 nm was obtained by TEM and SEM with or without PVP, indicating extensive agglomeration during preparation for microscopy. In contrast, without PVP stabilization, mean and mode sizes of respectively 35 ± 18 and 21 nm by spICPMS and 33 ± 15 and 20 nm by FI-spICPMS were obtained for suspensions of Ni NPs using external calibration with Ni standard solutions. With PVP stabilization, the mean and mode sizes respectively decreased to 27 ± 12 and 18 nm by spICPMS and 25 ± 10 and 16 nm by FI-spICPMS. Mass balance taking into account the amount of dissolved Ni was verified in all cases. No degradation in performance resulted from using FI-spICPMS instead of spICPMS, even though measurement of NPs mass by FI-spICPMS is done without knowledge of the transport efficiency and the sample uptake rate. This is the first time that spICPMS and FI-spICPMS are demonstrated to be suitable for the characterization of ferromagnetic NPs.