Nanoparticle characterization by electrical field-flow fractionation and single particle inductively coupled plasma mass spectrometry

Electrical field-flow fractionation (ElFFF) is a sub-technique of field-flow fractionation utilized for separation of charged nanoparticles. ElFFF was applied for characterization of size and charge of nanoparticles by investigating the nanoparticle retention time. However, one of the parameters; i.e., size or charge of nanoparticles, must be known before characterizing another parameter. This work illustrates an application of normal ElFFF for nanoparticle characterization associated with single particle inductively coupled plasma mass spectrometry (SPICP-MS) which was used for size determination. Six nanoparticles samples including 30 nm AuNPs stabilized by citrate, 60 nm AuNPs stabilized by citrate, mixture of 30 nm and 60 nm AuNPs stabilized by citrate, 60 nm silver nanoparticles (AgNPs) stabilized by polyethylene glycol (PEG), 100 nm AgNPs stabilized by citrate, and mixture of 60 nm AgNPs stabilized by PEG and 100 nm AgNPs stabilized by citrate were used as samples. The nanoparticles were prior separated in ElFFF system under 1.50 V applied voltage in deionized (DI) water carrier, then their fractions were collected for size determination using SP-ICP-MS. The charge, electrophoretic mobility, of nanoparticles was characterized by using the size determined from SP-ICP-MS and the retention time of nanoparticles via the ElFFF theoretical equation. The size and charge of nanoparticles characterized using ElFFF and SP-ICP-MS were in agreement with their size and charge reported in certificate. In addition, the size information obtained from ElFFF and SP-ICP-MS was applied for characterization of the layer thickness of stabilizing agent coated on nanoparticle surface of 60 nm AgNPs stabilized by PEG. With high sensitivity of inductively coupled plasma mass spectrometry (ICP-MS), this method shows potential use for characterization of nanoparticles in environmental system.