Contribution to Accurate Spherical Gold Nanoparticles Size Determination by Single Particle Inductively Coupled Mass Spectrometry: a Comparison with Small Angle X-ray Scattering
Abstract
Small Angle X-rays Scattering Spectroscopy (SAXS) is the method of choice for nanoparticle diameter and concentration determination. It is metrologically traceable for spherical nanoparticle mean diameter determination and does not require any sample preparation or calibration. On the other hand, Single Particle ICPMS (SPICPMS) is still under developments and requires involved process clarification and accuracy improvement. The strategy of this study is the comparison of the two techniques to study comprehensively SPICPMS performance and observe phenomena otherwise hidden. 6 spherical gold nanoparticle suspensions distributed over a large size range (30, 50, 60, 80,100 and150 nm) are studied as standards. Potential matrix effect are eliminated by stabilizing nanoparticles with chitosan in HCL. Chitiosan encapsulates nanoparticles, stabilizes their dispersion and protects them from dissolution. Detection counting/analog threshold and timeout appear as the relevant parameters for transient signals. They show an influence not only on mean signal but also on signal distribution. The detection tuning proposed allow to linearly calibrate the nanoparticle distribution signal to cubed diameter over the entire range studied with no sensitivity diminution. Comparing the 3 classical transport efficiency methods, size transport efficiency is shown as the most accurate. The new procedure is validated analyzing three gold nanoparticles suspensions (135, 40 and 50nm). The results are consistent with SAXS measurements.
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