title: Size determination and quantification of engineered cerium oxide nanoparticles by flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry.
abstract: Facing the lack of studies on characterization and quantification of cerium oxide nanoparticles (CeO2 NPs), whose consumption and release is greatly increasing, this work proposes a method for their sizing and quantification by Flow Field-flow Fractionation (FFFF) coupled to Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Two modalities of FFFF (Asymmetric Flow- and Hollow Fiber-Flow Field Flow Fractionation, AF4 and HF5, respectively) are compared, and their advantages and limitations discussed. Experimental conditions (carrier composition, pH, ionic strength, crossflow and carrier flow rates) are studied in detail in terms of NP separation, recovery, and repeatability. Size characterization of CeO2 NPs was addressed by different approaches. In the absence of feasible size standards of CeO2 NPs, suspensions of Ag, Au, and SiO2 NPs of known size were investigated. Ag and Au NPs failed to show a comparable behavior to that of the CeO2 NPs, whereas the use of SiO2 NPs provided size estimations in agreement to those predicted by the theory. The latter approach was thus used for characterizing the size of CeO2 NPs in a commercial suspension. Results were in adequate concordance with those achieved by transmission electron microscopy, X-ray diffraction and dynamic light scattering. The quantification of CeO2 NPs in the commercial suspension by AF4-ICP-MS required the use of a CeO2 NPs standards, since the use of ionic cerium resulted in low recoveries (99 ± 9% vs. 73 ± 7%, respectively). A limit of detection of 0.9 μg L(-1) CeO2 corresponding to a number concentration of 1.8 × 1012 L(-1) for NPs of 5 nm was achieved for an injection volume of 100 μL.
authors.affiliation: Group of Analytical Spectroscopy and Sensors (GEAS), Institute of Environmental Sciences (IUCA), University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain. Electronic address: laurasg@unizar.es.
authors.forename: L
authors.initials: L
authors.lastname: Sánchez-García
authors.affiliation: Group of Analytical Spectroscopy and Sensors (GEAS), Institute of Environmental Sciences (IUCA), University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Bolea
authors.affiliation: Group of Analytical Spectroscopy and Sensors (GEAS), Institute of Environmental Sciences (IUCA), University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Laborda
authors.affiliation: Group of Analytical Spectroscopy and Sensors (GEAS), Institute of Environmental Sciences (IUCA), University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Cubel
authors.affiliation: Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Chilton OX11 0DE, UK.
authors.forename: P
authors.initials: P
authors.lastname: Ferrer
authors.affiliation: Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Chilton OX11 0DE, UK.
authors.forename: D
authors.initials: D
authors.lastname: Gianolio
authors.affiliation: ISIS Facility, Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX, UK.
authors.forename: I
authors.initials: I
authors.lastname: da Silva
authors.affiliation: Group of Analytical Spectroscopy and Sensors (GEAS), Institute of Environmental Sciences (IUCA), University of Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
authors.forename: J R
authors.initials: JR
authors.lastname: Castillo
mesh_terms: D002563:Cerium / Q000032:analysis* / Q000737:chemistry; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D031521:Fractionation, Field Flow; D013058:Mass Spectrometry; D053768:Metal Nanoparticles / Q000032:analysis* / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D012822:Silicon Dioxide; D013057:Spectrum Analysis; D013535:Suspensions; D014961:X-Ray Diffraction
chemical_list: D013535:Suspensions; D002563:Cerium; C030583:ceric oxide; D012822:Silicon Dioxide
keywords: Cerium oxide nanoparticles; Flow Field-Flow Fractionation; Inductively Coupled Plasma Mass Spectrometry; Quantification; Size characterization; Suspension stability