Advanced analytical techniques for the measurement of nanomaterials in complex samples: a comparison

Abstract

To solve the various analytical challenges related to the measurement of nanomaterials in complex matrices new advanced analytical techniques must be developed. In this study an interlaboratory exercise was organised to compare the capabilities and limitations of newly developed techniques with classical techniques. Classical techniques involved were: (1) dynamic light scattering (DLS); (2) transmission electron microscopy (TEM); and (3) scanning electron microscopy (SEM). The newly developed techniques were: (1) single-particle inductively coupled mass spectrometry (sp-ICPMS); (2) nano tracking analysis (NTA); (3) differential centrifugal sedimentation (DCS); and (4) particle induced x-ray emission (PIXE). The results show that methods based on completely different physical principles, such as TEM, DLS, DCS, sp-ICPMS and PIXE, can produce similar results for pure suspensions of metallic nanoparticles. Electron microscopy (TEM and SEM) and sp-ICPMS were more accurate for size determination than NTA, DLS and DCS, while sp-ICPMS and PIXE were most accurate in the determination of mass concentrations of nanoparticles in pure suspensions. If an organic matrix was present the detection and sizing of nanoparticles became more difficult, especially for microscopic techniques, while light scattering methods like DLS and DCS detected multiple particle sizes. sp-ICPMS and NTA showed accurate results for the determination of particle size in chicken digest as well as in 10% DMEM, while only sp-ICPMS showed accurate results for mass concentrations in these complex matrices.