Single particle inductively coupled plasma mass spectrometry (spICP-MS) is a relatively new method of analysing ENMs which allows accurate and repeatable measurement of both the ENM size and concentration. Unlike its predecessor ICP-MS which only measures ionic metals, spICP-MS can distinguish between ionic and particulate forms of an element in the same sample. This means that the proportion of dissolved metal (or even dissolution rate) can be determined in situ in a sample rather than having to separate the dissolved and particulate fractions and measure them separately, which is fraught with potential for loss of sample and which can itself drive dissolution leading to unrealistic dissolution numbers. spICP-MS can also be used to confirm uptake of ENMs into organisms, and the presence of ENMs in specific tissue samples, rather than just using total metal content as given by ICP-MS. In NanoFASE, spICP-MS has been used to assess ENM bioaccumulation in organisms, as well as to demonstrate precipitation of metal ENMs in situ by organisms such as the isopod. spICP-MS is also used in NanoFASE to track biometallic (core-shell or chemically doped) ENMs in complex environments, such as the detection of Ho@TiO₂ ENMs in river water or in WWTPs where there is a high natural background of TiO₂.

Measurement principle: The particle is ionised within the spICP-MS instrument which is calibrated to measure the abundance at a specific mass of the known elements within the particle. The elements are treated by the instrument as being distinct individual particles and are given particle masses. The elemental masses are used to calculate elemental spherical diameters and particle volumes, from which the particle diameter is determined. For multi-element ENMs (e.g. Ho@TiO2 ENMs) it is assumed that all measured elements are the constituent elemental parts of one multi-element particle. Elemental volumes are calculated from the elemental diameters and summed to form the total particle volume, with the total particle diameter calculated from the total particle volume.

Used in
Determination of ENM dissolution  Ho@TiO2 core-shell case study	spICP-MS analysis of chemically doped or core-shell ENMs Nanopesticide case study

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Cui X, Fryer B, Zhou D, Lodge R, Khlobystov A, Valsami-Jones E, Lynch I. Core-shell NaHoF4@TiO2 NPs: A Labelling Method to Trace Engineered Nanomaterials of Ubiquitous Elements in The Environment. ACS Applied Materials & Interfaces, 2019, 11, 19452-19461. https://pubs.acs.org/doi/10.1021/acsami.9b03062

Analysis of SiO2 Nanoparticles in Standard Mode with Single Particle ICP-MS. PerkinElmer Application Note, undated.

Contact

Xianjin Cui

 

 

 

 

Iseult Lynch

University of Birmingham

i.lynch@bham.ac.uk