Calibration of single-particle inductively coupled plasma-mass spectrometry (SP-ICP-MS)

Abstract

We have identified incomplete particle vaporization and non-linear detector response as the major factors that cause the non-linearity of SP-ICP-MS measurements at high particle mass. The contribution of incomplete vaporization to the deviation from the linearity of the ICP-MS intensity is estimated using a mathematical model of particle vaporization. The non-linear detector response in the pulse-counting mode is due to the overlapping of the analyte ions at the detector within the 40 ns dead time of the electron multiplier. The overlap can be severe because of the relatively short pulse duration of 300 ms of the ion plumes of the discrete sample particles. The non-linear detector response has been modeled using Poisson statistics. We have also examined the applicability of calibration methods based on the standard particles, discrete standard solution droplets, and continuous nebulization of standard solution. The standard-solution calibration method requires linear calibration curves. The method may also suffer from errors due to the difference in the sensitivity of the standard solution and sample particles.Calibration using standard particles and discrete standard solution droplets do not have these limitations.

Detection, characterization and quantification of inorganic engineered nanomaterials: A review of techniques and methodological approaches for the analysis of complex samples

“…This means that solid samples must undergo some sample treatment for the digestion of the matrix, whereas suspensions could be directly analyzed. In any case, the feasibility of the direct analysis of suspensions by ICP-MS depends on the composition and size of the particles [115]. Suspensions of SiO 2 particles up to 1-2 µm have been successfully analyzed by using dissolved standards [116], as well as other metal and metal oxide nanoparticles below ca.…”

“…100 nm [117], proving that particulate and dissolved species behave in the plasma in a similar way. However, this behaviour cannot be extended to any nanoparticle [115].…”

“…properties of the NPs can lead to their incomplete vaporization in the ICP, resulting in inaccurate results depending on the size and nature of the NPs [121].…”

Double-Viewing-Position Single-Particle Inductively Coupled Plasma-Atomic Emission Spectrometry for the Selection of ICP Sampling Position in SP-ICP Measurements

“…It has been shown that the degree of vaporization, as well as the linear dynamic range of the single-particle calibration curve, can be increased by increasing the sampling depth so as to provide more time and higher gas temperature for particle vaporization. 33 The degree of vaporization of a 250-nm Au nanoparticle increases from 70 to 92% by increasing the sampling depth of a 1400-W ICP from 5 to 10 mm. 33 To avoid underestimation of the particle size by standard solution calibration, SP-ICP-MS measurement at a position where the sample particles are completely vaporized is vital.…”

Acquisition of fast transient signals in ICP-MS with enhanced time resolution

“…Although this form of analysis remains popular, alternative sampling approaches that produce a transient signal profile are now common. In recent years there has been a rise in single cell [1][2][3][4] and single particle 5,6 applications, where the analyte is diluted heavily before nebulisation, such that signals from individual particles or cells appear as single events. Several groups have reported the use of micro-droplet generators (µDG), which deliver discrete droplets to the ICP-MS with up to 100% transport efficiency.…”