Nano Measurement Techniques
Nanomaterials have tremendous potential in resolving current developmental and societal dilemmas, including health care and our increasing energy needs. The assessment and research of nanomaterials are defined by the European Union (EU) in various documents and, therefore, can make it hard to identify a clear research path for nanoparticle assessment. It is therefore increasingly relevant to measure the Nanomaterials on several qualifications such as size, shape, and toxicology to assess their potential to be harmful to humans, animals, as well as the environment.

How does one define a Nanomaterial?

The definition stated by the European Commission’s (EC) recommendation as followed: “The term nanomaterial is a natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50 % or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 – 100 Nanometer”

Nano Measurement Techniques compared to Bulk solids analysis techniques
The properties of nanomaterials are different from the bulk material and these need to be included in the REACH regulation requirements. What distinguishes Nanomaterials from non-Nano materials is that the Nanomaterials (NM for short) have a greater specific surface area by volume than bulk materials, however, this only applies if the bulk materials are non-porous. If the Bulk materials are porous particles within the micrometer dimensions range they can also have a high surface area but are of the non-nano materials variety. Therefore, relative to particles of a greater size the properties of the NMs are altered. When conducting a risk assessment, these features have to be considered, since nanomaterials are not intrinsically hazardous. For this reason, a specific description for the identification of nano is important.

Nano Measurement Techniques Screening and confirmatory methods

In general, the measurement methods are divided into two methodologies, screening, and confirmatory methods.

In addition, there is a distinction between approaches for general use and non-general use.

 Techniques used in screening methods

  • Several methods exist that allow for a fast and loose assessment of particle sizes.
  • The methods usually do not determine the number-based distribution of the external dimension(s).
  • They allow confirming that a material should be classified as a nanomaterial if the measured median diameter is less than 100 nm.
  • If the measured median diameter is larger than 100 nm, no conclusion with respect to the EC NM definition can be drawn and confirmatory methods must be used if no further information on the material is available.

Techniques used in confirmatory methods

  • Confirmatory methods are used for an in-depth characterization of the particle size distribution of a material.
  • They are needed when screening methods cannot be applied or do not provide the necessary results for a reliable classification.
  • They should be able to identify and measure constituent particles within aggregates and agglomerates.
  • The methods must be capable to deal with non-spherical particles and polydisperse particle size distributions.
  • They should provide the number-based particle size distribution as raw data

Delft Solids Solutions’ Nano measurement techniques

DSS has over the past few years specialized it’s services further gearing towards nanoparticle research methods relevant to the registration of materials in the European Union and concerning the regulations of the European Commission.

We have grouped the crucial analysis techniques, such as;

  • The BET method (screening), which is based on the assessment of the monolayer volume by means of physical gas adsorption at low temperatures. Based on this outcome, it is possible to calculate the Volume Specific Surface Area (VSSA) and this can be translated to the mean equivalent sphere diameter;
  • Dynamic Light Scattering (DLS), is based on photo-correlation spectroscopy. Fluctuations of scattered light are measured by Brownian motion. The outcome of this experiment is the spherical hydrodynamic Particle Size Distribution (PSD);
  • Scanning Electron Microscopy, the electron beam is focused on the sample and scanned over a defined area of the sample. Images are constructed based on electrons coming from the sample surface. Number-weighted size distributions are analyzed by identifying particles individually;
  • Transmission Electron Microscopy, part of the electron beam passes through a thin specimen. Images are constructed based on electrons passing through samples. Number-weighted size distributions are analyzed by identifying particles individually.

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Our approach

By having all crucial measurement techniques available, we can operate optimally in the field of nanoparticle research for our clients. These research techniques for nanomaterials are detailed in the Nanodefine Methods Manual, which is closely linked to the Recommendation of the European Commission on the Concept of Nanomaterials (2011/696 / EU).

These nanoparticle testing activities are needed in regards to the more stringent REACH registrations. The huge variety of documents available on the EC website and can make it hard to identify a clear research path for nanoparticle assessment. As Delft Solids Solutions we would like to facilitate this process and as such we can surely assist you in your nanomaterial testing needs.

A new disc centrifuge was recently acquired

Recently we have expanded our service with a new Disc Centrifuge, its measurement principle is based on sedimentation time and the fact that larger particles sediment faster than smaller particles. Knowing the particle density and centrifugal force, the Stokes equivalent sphere diameter can thus be calculated.

To meet the Nanomaterials business units’ ambitions, we recently obtained a new disc centrifuge: the DC24000UHR produced by CPS Instruments.

We specifically selected this unit for the following specifications:

It’s an analytical instrument for ultra-high resolution coupled to particle size distribution calculation with high precision. The functional range of the analyzer is from 2 nm to 80 microns (depending on sample density), providing the unique ability to address very similar multimodal particle distributions and to discern extremely small changes in particle size.

The instrument utilizes the technique of Differential Centrifugal Sedimentation (DCS) particle sizing. The Disc Centrifuge physically separates the nanoparticles instead of using a statistical algorithm and then tests them as they pass through a light source detector-offering full real-time characterization.

Delft Solids Solutions to gain second place in the NENnovation awards 2020

Out of all participants in our category, we were voted as the top three finalists. We are proud to announce that on the 16th of October Delft Solids Solutions was voted 2nd place by the NEN jury for the NENnovation Award 2020. The jury rapport in part stated:

“The jury is of the opinion that the NANOdrum of Delft Solids Solutions can offer a good solution for a socially very relevant issue regarding the (possibly harmful) effects of nanoparticles. The upcoming requirements from the European Commission will ensure greater attention from market parties, as a result of which the intended roll-out is considered realistic. There is good evidence and a strong link with standardization.

All things considered, the jury is of the opinion that Delft Solids Solutions has a well-deserved solid second place in the NENnovation Awards 2020 with the NANOdrum!”