Extraction and quantification of metal-containing nanoparticles in marine shellfish based on single particle inductively coupled plasma-mass spectrometry technique

Quantitative characterization of nanoparticles (NPs) in marine shellfish is critical to understanding the risks of bio-accumulation. Based on single particle (sp)ICP-MS and electron microscopy, a standardized protocol was developed to extract Ag, Au, and indigenous Ti-containing NPs from mussels. The optimal parameters are: dry sample extraction with tetramethylammonium hydroxide (TMAH), 5% (v/v) final concentration of TMAH, extraction at 25 celcius for 12 h, and separation by centrifugation (3000 rpm for 5 min). The particle number recoveries of spiked Ag and Au NPs were 88 +/- 0.9% and 95 +/- 1.1%, respectively, while Ti-containing NPs had a particle number concentration of 8.2 x 10(6) particles/mg and an average size of 70 nm in tested mussels. Furthermore, titanium oxide NPs, including rutile, anatase, and Magne ' li phases (TixO2x-1) were found ubiquitously in 10 shellfish based on the optimal method. The particle number concentrations and average sizes of the Ti-containing NPs were 2.1 x 10(6)-8.4 x 10(6) particles/mg and 70-80 nm, respectively. These Ti-containing NPs, such as TiO2, accounted for about half of the Ti mass in shellfish, indicating that marine shellfish may be a significant sink for Ti-containing NPs.