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.

Fungal synthesis of size-defined nanoparticles

“…mass, volume, number, intensity and average particle size can be obtained by AFM, AF4 and DLS and are equivalent for highly monodisperse hard spheres [92]. Barahona et al advised an approach using multimodal mixtures of monodispersed silica NPs standards with the use of the AF4-ICP-MS method for the coincident size and concentration ascertainment of this kind of NPs in an aqueous suspension [89].…”

Size determination and quantification of engineered cerium oxide nanoparticles by flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry

“…The second method was based on the use of size standards, so that the relationship between retention time and size can be established for fixed flow conditions [e.g. 23,24,25,26]. Single monodisperse suspensions of Ag NPs (10 nm from PlasmaChem, Berlin, Germany; 40 nm and 100 nm from Sigma Aldrich, Saint Louis, USA), and SiO 2 NPs (10 nm and 20 nm from PlasmaChem, Berlin, Germany; and 150 nm from Sigma Aldrich, Saint Louis, USA) were injected and their known size (core-particle size) plotted against the resulting retention ratio R. The curve-fitting equations were then determined for the two NP types according to Eq.…”

“…For the size calibration with NP standards, different NPs suspensions of known size can be used. A commonly used size reference standard are the traceable polystyrene-latex (PCL) beads or spheres [21,24,26,38,39]. Ideally, calibration with size standards of different composition requires elution times solely determined by their diffusional behaviour, so FFFF run conditions have to be optimized separately for both size standards and samples [40].…”

Porous nano-structured micro-granules from silica-milk bi-colloidal suspension: Synthesis and characterization

“…Meso/macro porous silica microgranules have been considered fascinating for various technological applications [18]. Such granules are used even in everyday commodities, such as abrasives in toothpaste [19], anti-caking agent in various powdered food items [20] or as fragrance and flavor carriers [21,22].…”