title: Simultaneous determination of size and quantification of silica nanoparticles by asymmetric flow field-flow fractionation coupled to ICPMS using silica nanoparticles standards.
abstract: This work proposes the use of multimodal mixtures of monodispersed silica nanoparticles (SiO2-NPs) standards for the simultaneous determination of size and concentration of SiO2-NPs in aqueous suspensions by asymmetric flow field-flow fractionation (AF4) coupled to inductively coupled plasma mass spectrometry (ICPMS). For such a purpose, suspensions of SiO2-NPs standards of 20, 40, 60, 80, 100, and 150 nm were characterized by transmission electronic microscopy (TEM), centrifugal liquid sedimentation (CLS), dynamic light scattering (DLS) and by measuring the Z-potential of the particles as well as the exact concentration of NPs by offline ICPMS. An online AF4-ICPMS method which allowed the separation of all the different sized SiO2-NPs contained in the mixture of standards was developed and the analytical figures of merit were systematically evaluated. The method showed excellent linearity in the studied concentration range (0.1-25 mg L(-1)), limits of detection between 0.16 and 0.3 mg L(-1) for smaller and greater particles, respectively, besides a satisfactory accuracy. AF4 calibration with particles with identical nature to those to be analyzed, also permitted accurate size determination in a pragmatic way. Similarly, by using prechannel calibration with NPs for mass determination it was possible to overcome common quantification problems associated with losses of material during the separation and size-dependent effects. The proposed methodology was successfully applied to the characterization in terms of size and concentration of aqueous test samples containing SiO2-NPs with monomodal size distributions.
authors: European Commission , Joint Research Centre, Institute for Health and Consumer Protection, Via E. Fermi 2749, 21027 Ispra, Varese Italy.
authors: Francisco
authors: F
authors: Barahona
authors: Otmar
authors: O
authors: Geiss
authors: Patricia
authors: P
authors: Urbán
authors: Isaac
authors: I
authors: Ojea-Jimenez
authors: Douglas
authors: D
authors: Gilliland
authors: Josefa
authors: J
authors: Barrero-Moreno