Quantifying silver and gold nanoparticles in water via carbazole fluorescence quenching: A simple and economical approach

Abstract

The fluorescence quenching of carbazole and carbazole@2-hydroxypropyl-β-cyclodextrin complex was evaluated in water as an analytical strategy for the quantification of six different silver and gold nanoparticles with either gallic acid, citrate, or p-(2-hydroxyethoxy) benzoic acid as ligands. The free carbazole is more sensitive to the analyzed metal nanoparticles with detection limits in the picomolar level (e.g., 0.106 pM for citrate-stabilized silver nanorods (AgNR) and 34.5 pM for citrate-stabilized silver nanospheres (AgNPc)) compared to the cyclodextrin-complexed carbazole (e.g., 0.200 pM for AgNR to insensitive for AgNPc). The recovery assays in spiked tap water and surface river water for all the analyzed nanoparticles were between 90 % and 112 % with 95 % confidence. The proposed method is an excellent alternative to more sophisticated methodologies for accurately quantifying silver and gold nanoparticles in aqueous systems.