ABSTRACT
Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) is a new tool that can provide the element composition, size distribution, and number concentration of nanoparticles. Here we discussed the effects of dwell time and settling time on analysis of nanoparticles by SP-ICP-MS. We analyzed standard materials of gold nanoparticles (30, 40 and 60 nm AuNPs, from NIST and NCNST), showing that better signal-to-noise ratio and higher determination efficiency could be achived when using shorter dwell time and settling time. We utilized a nano mode for SP-ICP-MS, in which the dwell time was set as 0. 05 ms and the settling time was 0. The size of NIST AuNP standard material determined here was in accord with the certified size using the developed method. The detection limits of size and number concentration of AuNPs were 8 nm and 1. 1×105 particle / L, respectively.
ABSTRACT
OBJECTIVES: Rapid increase in engineered nanoparticles (ENPs) in many goods has raised significant concern about their environmental safety. Proper methodologies are therefore needed to conduct toxicity and exposure assessment of nanoparticles in the environment. This study reviews several analytical techniques for nanoparticles and summarizes their principles, advantages and disadvantages, reviews the state of the art, and offers the perspectives of nanometrology in relation to ENP studies. METHODS: Nanometrology is divided into five techniques with regard to the instrumental principle: microscopy, light scattering, spectroscopy, separation, and single particle inductively coupled plasma-mass spectrometry. RESULTS: Each analytical method has its own drawbacks, such as detection limit, ability to quantify or qualify ENPs, and matrix effects. More than two different analytical methods should be used to better characterize ENPs. CONCLUSIONS: In characterizing ENPs, the researchers should understand the nanometrology and its demerits, as well as its merits, to properly interpret their experimental results. Challenges lie in the nanometrology and pretreatment of ENPs from various matrices; in the extraction without dissolution or aggregation, and concentration of ENPs to satisfy the instrumental detection limit.
Subject(s)
Limit of Detection , Microscopy , Nanoparticles , Spectrum AnalysisABSTRACT
Asingleparticle-inductivelycoupledplasmamassspectrometric(SP-ICP-MS)methodwas established to detect the size distribution and number concentrations of silver nanoparticle ( AgNPs) in dilute aqueous solution. The optimal dwell time was 3 ms to reduce possibility of two or more particles entering into detector simultaneously. An iterative algorithm was applied to distinguish AgNPs as outliers from baseline and dissolved metal ion signal if the measured intensity was beyond five time standard deviation of whole data. Size distribution and number concentration of three commercial silver nanoparticle dispersions ( nominal diameters of 30, 50, 100 nm) were determined using SP-ICP-MS. The result of SP-ICP-MS is accurately similar to the transmission electron microscopy ( TEM) , indicating that SP-ICP-MS is able to size silver nanoparticles. The particle size detection limit is 25 nm and the limit of number concentration is 8 × 104 particles/L in dilute solution. Tap water added with silver nanoparticle was tested to obtain a similar size distribution and number concentration. This method is simple, fast and highly sensitive, which can be used to investigate risk assessment of silver nanoparticle in aqueous environment and monitor silver nanoparticle in drinking water.