A robust size-characterisation methodology for studying nanoparticle behaviour in ‘real’ environmental samples, using hydrodynamic chromatography coupled to ICP-MS

Abstract

A hyphenated methodology has been developed and validated, which utilizes the extensive size separation range of hydrodynamic chromatography (here: 5–300 nm) combined with the multi-element selectivity of ICP-MS. This has been applied to the analysis of metal-based nanoparticles in environmental samples. The quality of the particle sizing data obtained from this exercise was enabled through the production of a range of gold nanoparticles (sterically stabilized to prevent aggregation in environmental matrices), which were validated for use as external size calibration standards as well as internal retention time markers, using TEM. The methodology was then successfully applied to a study where nanosilver was spiked into sewage sludge, preliminary data from which showed that a fraction of nanosilver survived as single nanoparticles in the sludge supernatant. The method was also tested on solutions containing other commonly used nanoparticles (TiO₂, SiO₂, Al₂O₃ and Fe₂O₃).

Overall, the data showed that, by using ICP-MS with collision cell technology, the methodology would be helpful in investigating the fate of a significant range of nanoparticle types. Other characteristics of HDC-ICP-MS are: rapid analysis time (<10 min), extended sizing range (5 to >300 nm), and limited sample pre-treatment required.