Cloud point extraction (CPE) combined with single particle -inductively coupled plasma-mass spectrometry (SP-ICP-MS) to analyze and characterize nano-silver sulfide in water environment.

Silver Nanoparticles (Ag-NPs), an emerging type of pollutant, might occur various physical and chemical transformations, which would affect its environmental fate, transformation and biological effects. Sulfurization is the most common conversion of Ag-NPs, accompanied by the formation of nano-silver sulfide (AgS-NPs). The method of AgS-NPs analysis and characterization is of great significance for assessing the environmental risks of Ag. In this study, cloud point extraction (CPE) and Single Particle-Inductively Coupled Plasma-Mass Spectrometry (SP-ICP-MS) were used in combination to establish a simple and reliable analysis method to quantify AgS-NPs in water, with the morphology unchanged. Non-AgS-NPs were dissociated into Ag firstly, and AgS-NPs and Ag were separated by CPE, followed by SP-ICP-MS analysis. The extraction rate based on particle number concentration was between (76.19 ± 0.56) % to (106.35 ± 0.00) % in environmental waters. Compared with the (76.96 ± 2.18) nm AgS-NPs spiked, the particle size extracted increased slightly with (94.19 ± 2.72) nm- (97.25 ± 0.22) nm as the large-size AgS-NPs originally presented in waters, instead of agglomeration. This method could be generally applicable to the analysis of AgS-NPs in waters, and provide ideas for other metal sulfide nanoparticles (MS-NPs), which has certain significance.