Detection, characterization and quantification of inorganic engineered nanomaterials: A review of techniques and methodological approaches for the analysis of complex samples

Abstract

The increasing demand of analytical information related to inorganic engineered nanomaterials requires the adaptation of existing techniques and methods, or the development of new ones.The challenge for the analytical sciences has been to consider the nanoparticles as a new sort of analytes, involving both chemical (composition, mass and number concentration) and physical information (e.g. size, shape, aggregation). Moreover, information about the species derived from the nanoparticles themselves and their transformations must also be supplied. Whereas techniques commonly used for nanoparticle characterization, such as light scattering techniques, show serious limitations when applied to complex samples, other well-established techniques, like electron microscopy and atomic spectrometry, can provide useful information in most cases. Furthermore, separation techniques, including flow field flow fractionation, capillary electrophoresis and hydrodynamic chromatography, are moving to the nano domain, mostly hyphenated to inductively coupled plasma mass spectrometry as element specific detector.Emerging techniques based on the detection of single nanoparticles by using ICP-MS, but also coulometry, are in their way to gain a position. Chemical sensors selective to nanoparticles are in their early stages, but they are very promising considering their portability and simplicity.Although the field is in continuous evolution, at this moment it is moving from proofs-of-2 concept in simple matrices to methods dealing with matrices of higher complexity and relevant analyte concentrations. To achieve this goal, sample preparation methods are essential to manage such complex situations. Apart from size fractionation methods, matrix digestion, extraction and concentration methods capable of preserving the nature of the nanoparticles are being developed. This review presents and discusses the state-of-the-art analytical techniques and sample preparation methods suitable for dealing with complex samples. Single-and multimethod approaches applied to solve the nanometrological challenges posed by a variety of stakeholders are also presented.

Regulatory ecotoxicity testing of nanomaterials – proposed modifications of OECD test guidelines based on laboratory experience with silver and titanium dioxide nanoparticles

“…A comprehensive characterization of the NMs is necessary to interpret the results. This topic is also addressed in various papers (Laborda et al, 2016;Montaño et al, 2014;OECD, 2012) and should be performed using the latest techniques, and at least following the recommendations in the OECD WPMN document (OECD, 2012). With the present compilation of recommended modifications to ecotoxicological test guidelines, elaborated in the scope of the EU-project MARINA, the further standardization of test guidelines for the testing of NMs shall be supported.…”

Mass spectrometry for the characterization and quantification of engineered inorganic nanoparticles

“…sp-ICP-MS has also been applied to assess the release of NPs from plastic food containers and to investigate the fate of different metal NPs in several in vitro studies (e.g. study of tissues of organism exposed previously to the NPs) [26].…”

“…Besides, the feasibility of size characterization, assessment of NPs mass percent, their isotopic abundance and stability for Ag nanowires, TiO2, ZnO and CeO2 NPs by sp-ICP-MS have been also reported [25]. Most recently, a critical review reports the detection and characterization of a wide variety of NPs (Au, Ag, TiO2 and SiO2, among others) in complex matrices, including wastewaters, blood, foods and biological tissues [26]. sp-ICP-MS has also been applied to assess the release of NPs from plastic food containers and to investigate the fate of different metal NPs in several in vitro studies (e.g.…”

“…Additionally, size distribution should be monitored to clarify whether free or aggregated NPs are in the samples both, in cellular internalization efficiency and in cytotoxicity studies. Therefore a special attention has been paid to the development of analytical methodologies able to provide accurate information in terms of NPs size distribution [26], being dynamic light scattering (DLS) and TEM two of the most popular and efficient approaches for such purposes.…”

Determination of emerging contaminants in environmental matrices

“…Linsinger and co-workers also reported on an inter-laboratory study evaluating the SP-ICP-MS measurements of Au-NPs standards (Linsinger et al, 2014). Regarding to the analysis of real samples, published applications include the characterisation of Ag-NPs released from plastic food containers (Ramos et al, 2016), analysis of Ag-NPs in environmental waters (Tuoriniemi et al, 2012) and wash waters (Mitrano et al, 2015) among some others (Laborda et al, 2016), but the applicability to real unknown and polydispersed samples still needs further research. Moreover, the development of systems for data analysis should be directed to fast, pragmatic and user-friendly tools, as contributions from researchers (Peters et al, 2015;Tuoriniemi et al, 2014) and manufacturers (Hineman and Stephan, 2014;Dan et al, 2015) already suggested.…”