Optimization of Nanoparticle Size and Count Measurements Using Nanoparticle Tracking Analysis (NTA)

D. Griffiths, S. Capracotta, J. Smith, I. Wilson, P. Hole
NanoSight Inc., US

Keywords: nanoparticle, size, count

Summary:

Nanoparticle Tracking Analysis (NTA) is the only automated method for counting particles as small as 10 nm and has gained increasing popularity for the study of nanoparticle dispersions, providing high-resolution particle size analysis as well as a direct measure of particle count or concentration. As these measurements have become more important to research in fields as diverse as virus, inorganic nanoparticles, exosomes, and protein aggregates, improvements in reproducibility and accuracy have been achieved through optimization of sampling statistics and analytical protocols. As a particle-by-particle analysis, the statistics required for optimum reproducibility and resolution need to be considered. The requirements for sufficient statistics depend on the requirements of the analysis and sample type. Analyzing increasing numbers of particles can be achieved by extending analysis times or by multiple sub-samplings. Data shows that a practical limit is reached beyond which increasing analysis time shows a diminished improvement in reproducibility. Multiple samplings show further improvement. Additionally, carrying out analyses under a constant slow flow rather than static provides a further significant improvement. For monodisperse, well-dispersed materials such as standards, short run times provide sufficient benefits. For polydisperse distributions, guidelines have been developed.