Characterization of nanoparticle suspensions using single particle inductively coupled plasma mass spectrometry
Karen E. Murphy, Jingyu Liu, Antonio R. Montoro Bustos, Monique E. Johnson, Michael R. Winchester
This NIST special publication (SP) is one in a series of NIST SPs that address research needs articulated in the National Nanotechnology Initiative (NNI) Environmental, Health, and Safety Research Strategy published in 2011 . This Strategy identified a Nanomaterial Measurement Infrastructure (NMI) as essential for science-based risk assessment and risk management of nanotechnology-enabled products as pertaining to human health, exposure, and the environment. NIST was identified as the lead federal agency in the NMI core research area of the Strategy; this research area includes measurement tools for the detection and characterization of nanotechnology-enabled products. Single particle inductively coupled plasma mass spectrometry (spICP-MS) is emerging as a promising analytical method for the characterization of nanoparticles (NPs) in natural matrices at environmentally relevant concentrations. The rapid development of spICP-MS for counting and sizing of NPs has resulted in a wide range of recommended metrological conditions for use in the implementation of this method. The objective of this SP is to establish a protocol for the determination of mean nanoparticle size (effective spherical particle diameter), number based size distribution, particle number concentration and mass concentration of ions in an aqueous suspension of NPs using spICP-MS. The example presented in this SP pertains to the measurement of gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) but the presented protocol is applicable to the measurement of all spherical nanoparticles containing elements measureable by ICP-MS. In addition, this protocol describes a Kragten spreadsheet approach for estimation of the expanded uncertainty of the spICP-MS particle size and particle number concentration measurement.