{"id":89,"date":"2025-07-02T18:11:05","date_gmt":"2025-07-02T18:11:05","guid":{"rendered":"https:\/\/libraryresources.nse.org.ng\/nanoengineering\/chapter\/laboratory-5\/"},"modified":"2026-03-16T14:21:06","modified_gmt":"2026-03-16T14:21:06","slug":"laboratory-5","status":"publish","type":"chapter","link":"https:\/\/libraryresources.nse.org.ng\/nanoengineering\/chapter\/laboratory-5\/","title":{"raw":"Laboratory 5 - Single Particle ICPMS","rendered":"Laboratory 5 – Single Particle ICPMS"},"content":{"raw":"
\n\nNote to readers:\u00a0<\/strong>Relevant theory for this laboratory on single paritcle ICPMS is typically expanded into two lectures. Here, we present only a short introduction to theory, a standards-reading exercise, and the procedures, data analysis, and discussion questions corresponding to a laboratory exercise. Theory sections may be expanded into additional chapters at a later time.\n\n<\/div>\n

1. Introduction<\/strong><\/h1>\nMultimodal or highly polydisperse samples of nanoparticles often present challenges for a comprehensive and accurate determination of the particle size distribution. Although \u201cbatch\u201d measurements on mixtures of particles can provide an averaged size and polydispersity measure, multimodal size distributions are generally difficult to resolve. Furthermore, the size determination may be biased if the measurement is more sensitive to a subset of the population, e.g., more strongly scattering particles, that obscures other particles in the population. Separation of the nanoparticles would enable different sub-populations to be characterized individually, thus reducing errors or interferences in the measurements. However, sample losses or transformations such as aggregation could occur during the separation process.\n\nSingle particle inductively coupled plasma mass spectrometry (spICPMS) is an advanced nanoparticle characterization method that takes advantage of the extremely high sensitivity of ICPMS analysis, along with the ability to selectively monitor specific elements, to evaluate the mass of individual nanoparticles<\/strong> in a population. The method can be applied for metal or inorganic nanoparticles, such as gold, silver, titanium dioxide, etc. The single-particle mode of ICPMS differs from standard ICPMS measurements, where samples are typically digested into dissolved ions for total concentration determination by evaluating the average signal intensity at the MS detector. Rather, the only sample processing for spICPMS is dilution, and individual particles are distinguished from dissolved ions as spikes in intensity, the height of which correlates to the mass of the element detected in the nanoparticle. An equivalent spherical diameter can then be computed if the composition of the nanoparticle (i.e. the molar mass ratio of the element detected versus the overall elemental composition) and the nanoparticle density are known.\n\nTwo types of calibration samples must be run to complete the analysis: (1) dissolved ionic standards at known concentrations, to correlate the signal intensity to the mass of the element detected, and (2) a nanoparticle standard of known concentration, to determine the transport efficiency, i.e. the fraction of nanoparticles that reach the detector relative to the known quantity of nanoparticles in the sample. The data processing also requires a routine to separate particle spikes from the background (ionic) signal. Given all the requisite data, the analysis can yield the following results: (1) ionic concentration; (2) particle number concentration; and (3) individual particle masses or sizes, which can be used to generate a histogram of the particle size distribution and determine the number-average size or other statistical features.\n\nThis laboratory will apply spICPMS for the analysis of a multimodal sample containing a mixture of commercial Au nanoparticles (nominally 10 nm, 30 nm, 60 nm, and 100 nm) and two Au nanoparticle samples synthesized in class with different colors (pink and purple). The learning objectives of the laboratory include: (1) evaluating advantages or disadvantages of spICPMS to characterize nanoparticle size distributions; (2) evaluating the data quality compared to performance standards in the ISO documentary standard for spICPMS; (3) comparing the observed results to expected results; and (4) critically evaluating the results.\n\nThe laboratory is paired with ISO\/TS 19590:2017 \u2014 Size distribution and concentration of inorganic nanoparticles in aqueous media via single particle inductively coupled plasma mass spectrometry<\/strong>. (It is noted that an updated standard has been published in 2024.)\n

2. Relevant Documentary Standards and Reading Exercises<\/strong><\/h1>\n
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Exercise L5.1<\/strong><\/p>\n\n<\/header>\n

\n\nReview the following ISO test standard:\n