Reliable Surface Analysis Data of Nanomaterials in Support of Risk Assessment Based on Minimum Information Requirements

Abstract

The minimum information requirements needed to guarantee high-quality surface analysis data of nanomaterials are described with the aim to provide reliable and traceable information about size, shape, elemental composition and surface chemistry for risk assessment approaches. The widespread surface analysis methods electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) were considered. The complete analysis sequence from sample preparation, over measurements, to data analysis and data format for reporting and archiving is outlined. All selected methods are used in surface analysis since many years so that many aspects of the analysis (including (meta)data formats) are already standardized. As a practical analysis use case, two coated TiO2 reference nanoparticulate samples, which are available on the Joint Research Centre (JRC) repository, were selected. The added value of the complementary analysis is highlighted based on the minimum information requirements, which are well-defined for the analysis methods selected. The present paper is supposed to serve primarily as a source of understanding of the high standardization level already available for the high-quality data in surface analysis of nanomaterials as reliable input for the nanosafety community.

Automation and Standardization—A Coupled Approach towards Reproducible Sample Preparation Protocols for Nanomaterial Analysis

“…Furthermore, coupling the preparation equipment with analytical tools or combining the preparation of biological samples with physicochemical methods allows new approaches for reliable correlative measurements. This is shown in 2.2 and is necessary for quantitative structure-activity relationships and modern methods in risk assessment [27]. On the other hand, automation is not feasible for sample preparation methods which are rarely used or require long experimental experience.…”

“…Central to ensuring reproducibility of sample preparation is the provision of a detailed process description including all relevant steps in a workflow; in other words, a standard operating procedure (SOP) [27]. Especially for scientific publications, an extensive step-wise description of the protocol should be a requirement.…”

Recent Advancements in the Nanomaterial Application in Concrete and Its Ecological Impact

“…Risk assessment examines the hazards to the health of humans and the environment of a sole substance at a specific point in its production time, service life, or discharge [158][159][160]. Risk assessment is regularly carried out to recognize if any stages of life cycle present a risk.…”

Surface chemistry of metal oxide nanoparticles: NMR and TGA quantification

“…Surface functional groups have a major impact on the behavior of nanomaterials since they are one of the main factors that control interactions with the surrounding environment. Despite their importance in determining the fate of nanomaterials that are used in nano-enabled products or inadvertently ingested or released to the environment, the identification and quantification of surface functional groups and coatings are considerably more challenging than measuring other important properties such as particle size distribution and composition [1][2][3][4]. Although surface chemistry is routinely used to stabilize nanomaterials against degradation and aggregation, to improve biocompatibility, and to provide functional groups for attachment of targeting moieties, it is relatively rare that surface groups are quantified, either for commercially available materials or for those produced on a laboratory scale.…”

“…Other methods such as conductometric titrations [11,19,20] and a range of optical assays [9,[21][22][23][24] provide information on functional groups that are accessible to the assay reagents, an important factor when the nanomaterial requires further surface functionalization prior to use. Surface analysis methods such as X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) have also been employed [3,4,[25][26][27].…”