A simple optical sensor for the simultaneous determination of trace amounts of silver and gold nanoparticles in water by cloud point microextraction

Nowadays, metal nanoparticles are widely used in many fields due to their excellent properties. This has led to an increasing presence of these species in water, which, although in very low concentrations, can cause damage to ecosystems. These nanomaterials are currently considered as emerging pollutants in water, so there is a need to know their concentrations. In particular, gold and silver nanoparticles are among the most widely used. Therefore, the development of simple methods that allow their determination even at trace concentrations is of interest. In this work, a method has been developed for the simultaneous determination of low concentrations of silver and gold nanoparticles (AgNPs and AuNPs, respectively) in water by cloud point microextraction using Triton X-114 as extractant and UV-Vis molecular spectrophotometry. It is a simple, environmentally friendly method with an easy-to-use portable instrument that requires only a microdrop of the extracted phase for the analysis of both species. Detection limits reached were 17 and 15 mu g L- 1 for AgNPs and AuNPs, respectively. The enrichment factors were 160 for AgNPs and 165 for AuNPs.