Separation and determination of silver nanoparticle in environmental water and the UV-induced photochemical transformations study of AgNPs by cloud point extraction combined ICP-MS

In this study, cloud point extraction (CPE) combined inductively coupled plasma mass spectrometry (ICP-MS) was used to determinate silver nanoparticles (AgNPs) in environmental water. AgNPs dispersed in water could be extracted into surfactant phase based on optimized CPE parameters which including pH, incubation temperature and equilibration time, the content of nonionic surfactants (Triton X-114, TX-114) and Na 2 S 3 O 3 . Good separation results of AgNPs and ionic silver Ag(I) in aqueous environment was obtained with the addition of Na 2 S 3 O 3 when the concentration of Ag(I) was lower than ten times of AgNPs. High recoveries of different diameter AgNPs spiked into ultrapure water were obtained. The influence of environmentally relevant matrix on CPE of AgNPs was studied in detail. Our results showed that there were little interference of environmentally relevant ions and five representative engineering nanomaterials (ENMs) on CPE of AgNPs. Moreover high recoveries and good separation were obtained when natural organic matter (NOM) up to 30   mg/L mixed with AgNPs in ultrapure water. The detection limit of AgNPs in water using CPE combined ICPMS was 5   ng/L. The recoveries of the AgNPs spiked into natural and effluents water with this method were in the range of 79±1–123±13%. Furthermore CPE-ICPMS and Single particle-ICPMS were used to study the UV induced photochemical transformations of AgNPs suspension at environmental relevant concentrations.