2019/05/03 by Kazuhiro Kumagai, Akira Kurokawa · 15 citations
Chemistry · Engineering · Materials Science · Mathematics · #Analytical Chemistry (journal) #Chemistry #Chromatography #Colloidal gold #Composite material #Electrohydrodynamics and Fluid Dynamics #Gold and Silver Nanoparticles Synthesis and Applications #Materials science #Mathematics #Nanomaterials and Printing Technologies #Nanoparticle #Nanotechnology #Particle (ecology) #Scanning electron microscope #Substrate (aquarium) #Suspension (topology)
paper · doi:10.1088/1681-7575/ab1f37
published in Metrologia 56(4), 044001 (IOP Publishing)
openalex publication_date 2019/05/03 · crossref created 2019/05/03 · crossref issued 2019/06/03 · crossref published 2019/06/03 · crossref published-online 2019/06/03 · crossref published-print 2019/08/01 · openalex created_date 2025/10/10 · crossref deposited 2026/02/07 · openalex updated_date 2026/07/28 · crossref indexed 2026/07/28
Abstract Measuring the number concentration (NC) of nanoparticles (NPs) in suspension has become important because of its use as an index of the quality and efficacy of medical and industrial products. Although scanning electron microscopy (SEM) can reveal individual particles, it is not commonly used for measurement owing to difficulties in sample preparation. We used a micro-liquid dispenser to prepare a specimen of a gold NP suspension, and by combining SEM and gravimetry we measured the NC. The dispenser places a small droplet of suspension onto a Si substrate without splashing, confining the particles in a small area. This method enabled us to observe and count all particles in the area by SEM without loss. The average weight of droplets was determined from weight increments of multiple ejections from the dispenser into a reservoir on an analytical balance. Dividing the NP number by single droplet weight gives NC in g −1 . Our simple method gave a precise measurement of the NC of Au NPs with a relative expanded uncertainty of <6% ( k = 2) by identifying all particles in a droplet.