The challenge
Instrument provider Malvern Panalytical approached NPL with its now-released Zetasizer Ultra dynamic light scattering instrument (DLS). One of the improved capabilities of this system is the ability to measure nanoparticle concentration, using a combination of multi-angle DLS (MADLS®) and adaptive correlation. However, the lack of suitable nanoparticle reference materials and traceable methods for measuring colloidal concentrations made the testing and validation of this and similar methods challenging. As one of the industrial collaborators of the NPL-led Innanopart project of the European Metrology Programme for Innovation and Research (EMPIR), Malvern Panalytical was aware of the expertise within NPL and wanted us to help validate this Particle Concentration method and benchmark it against the capabilities of other Malvern Panalytical products.
The solution
We were able to provide both the materials and know-how to effect this successful comparison. We hosted engineers from Malvern Panalytical in the our labs and worked with them using well-characterised nanoparticle materials with known colloidal concentrations already measured by other methods. Working with scientists at NPL, Malvern Panalytical could test, validate and benchmark this Particle Concentration analysis feature in the new Zetasizer Ultra and are currently drafting a co-authored journal paper about their findings.
The impact
Nanoparticles are increasingly used in innovative advanced products and provide enhanced, unique properties of great commercial and societal value. The measurement of the number concentration of colloidal particles is of major commercial interest as it: enables the optimisation of materials specification and design; is essential for risk assessment and quality control; supports compliance with regulatory requirements; and underpins claims to reliability, performance and lifetime in the formulation of products containing particles.
The stakeholder community now has increasing confidence in the tools available to them for the measurement of colloidal concentration. Previously, whilst DLS has, in theory, been able to calculate number concentration, it has been notoriously sensitive to impurities and has therefore had limited application. DLS is a widely-used and available technique and, having a more robust concentration analysis feature within the Zetasizer Ultra, makes such measurements more accessible to researchers going forward.