Size Uncertainty in Individual Nanoparticles Measured by Single Particle Inductively Coupled Plasma Mass Spectrometry

Abstract

Single particle inductively coupled plasma mass spectrometry has been used for size measurements of individual nanoparticles (NPs). Here, uncertainties in size analysis based upon two calibration approaches were evaluated: (i) the use of particle size standard and (ii) the use of ion standard solution. For particle size standard approach, the source of uncertainty to determine the target NP diameter was related to the variation in the signal intensities of both target NPs and particle size standard, and the size distribution of the particle size standard. The relative uncertainties of the 50 nm silver NP as the target were 15.0%, 9.9%, and 10.8% when particle size standards of 30 nm, 60 nm, and 100 nm silver NPs were used, respectively. As for the ion standard solution approach, the sources of uncertainty were the concentration of working standard solution, sample flow rate, transport efficiency, slope of calibration curve, and variation in the signal intensity of the ion standard solution and of the target NPs. The relative uncertainties for the 50 nm silver NP were 18.5% for 1 ng/g, 7.6% for 10 ng/g, and 4.7% for 100 ng/g solutions. The lower uncertainty obtained with a high concentration working standard solution is recommended to improve precision on particle size determinations by spICP-MS.

Particle Size Measurement and Detection of Bound Proteins of Non-Porous/Mesoporous Silica Microspheres by Single-Particle Inductively Coupled Plasma Mass Spectrometry

“…Particle size measurements by spICP-MS were based on a conventional calibration approach using an ion standard solution (i.e., the ion standard solution approach) [ 33 , 34 ]. This approach uses a mass flux calibration curve from ion standard solutions and determines the particle size from the mass of the target particle, assuming a spherical geometry.…”

“…Here, is the particle density and is the overall porosity (described below in detail). In the case of the non-porous SiO 2 microspheres, the particle density (simply called ) was assumed to be equal to the density of the bulk material (2.65 g/cm 3 for SiO 2 ), similar to the assumption made in many previous studies [ 32 , 33 , 34 ]. In the case of the mesoporous SiO 2 microsphere, the particle density ( ) was measured as the “true density” using the gas pycnometry method following the procedure in the ISO 12154:2014 standard [ 35 ] and using a BELPycno helium pycnometer (MicrotracBEL, Osaka, Japana).…”

Particle size Measurement and Detection of Bound Proteins of non-Porous/Mesoporous Silica Microspheres by Single-Particle Inductively Coupled Plasma Mass Spectrometry

“…Particle size measurements by spICP-MS are based on a conventional calibration approach using an ion standard solution (i.e., the ion standard solution approach) [24,25]. This approach uses a mass flux calibration curve from standard ion solutions and determines the particle size from the mass of the target particle, assuming a spherical geometry.…”

ICP-MS-Based Characterization and Quantification of Nano- and Microstructures

“…Despite considerable progress being made, SP-ICP-MS is still considered an emerging technique, with many advancements yet to come before it can be considered an established methodology. In fact, three examples of metrological advances and efforts to expand the measurement capabilities and consolidate the role of SP-ICP-MS for the characterization of NPs are included in this Special Issue [9][10][11]. The evaluation of SP-ICP-MS size uncertainty of individual NP diameter indicates that the relative uncertainty in the diameter increases as the NP size decreases regardless of the size of the NP calibration standard [9].…”

“…In fact, three examples of metrological advances and efforts to expand the measurement capabilities and consolidate the role of SP-ICP-MS for the characterization of NPs are included in this Special Issue [9][10][11]. The evaluation of SP-ICP-MS size uncertainty of individual NP diameter indicates that the relative uncertainty in the diameter increases as the NP size decreases regardless of the size of the NP calibration standard [9]. Higher precision in the analysis of individual NP diameters can be achieved when using NP calibration standards with a narrower size distribution.…”