The fluorescence quenching of rhodamine 6G as an alternative sensing strategy for the quantification of silver and gold nanoparticles

A method for the quantification of 22-26 nm gold (AuNP) and 10-20 nm silver nanoparticles (AgNP) was developed using the fluorescence quenching of rhodamine-6G. This fluorescent probe detected the different metal nanoparticles (MNP) at the pmol L-1 level (3.6 to 15.6 pmol L-1) depending on the type of nanoparticle) in phosphate buffer solutions at pH 6.94. The method was validated at the 95% confidence level using recovery tests to spiked drinking and surface river water (before and after industries). For AuNP@citrate26 and AgNP@SDDC12, the overall average recoveries ((R) over bar) were 90% (RSD: 11%) and 82% (RSD: 10%) in drinking water, respectively. Whereas, in surface river water before and after industries, (R) over bar were 88% (RSD: 17%) and 93% (RSD: 11%) for AuNP@citrate26, correspondingly; and 94% (RSD: 6%) and 83% (12%) for AgNP@SDDC12, respectively. The proposed strategy represents an accurate, rapid, simple, and cost-effective methodology to analyze MNP in aqueous systems.