Analytical strategies to the determination of metal-containing nanoparticles in environmental waters

Metal-containing nanoparticles (MNPs) represent emerging pollutants that still pose analytical challenges for their determination in environmentally relevant samples, including extremely low MNPs' concentrations, high colloidal background and the need to perform speciation analysis. Complementary to traditional state-of-the-art techniques evaluated elsewhere, this review additionally evaluates less conventional approaches for sample pretreatment, preconcentration, on- and offline detection, size characterisation and quantification of MNPs in environmental samples. Preconcentration techniques, like cloud point extraction and solid phase extraction, provide high preconcentration factors and recoveries. Electrothermal atomic absorption spectrometry opens interesting perspectives in the still unresolved distinction between dissolved ions and nanoparticles. Combination of single particle ICP-MS with size fractionation techniques, like hydrodynamic chromatography or electrospray-differential mobility analysis, is highly promising for assessment of shape and structure related information of MNPs and their aggregates. Although highly relevant, the validation and production of reference materials and quantitative criteria on measurement certainty still require further development. (C) 2016 Elsevier B.V. All rights reserved.