A simple, selective, and rapid detection-cum-precipitation of hazardous gold nanoparticles and their discrimination from gold(III) in environmental samples by a chromofluorogenic probe

This article describes the development of a highly selective, quick, and simple technique for the detection-cum-precipitation of gold nanoparticles (AuNPs) in an aqueous medium at ultra-low concentration. Upon addition of 1, which has been synthesized via a one-step reaction between 2-formylphenylboronic acid and 6-amino-2-mercaptobenzothiazole, to the aqueous solution of AuNPs, showed a naked eye observable instant color change from pink to blue via boroxine ring induced assembly. Upon mixing 1 with AuNPs, dark blue precipitates formed rapidly via aggregation. Thus, demonstrating a simple precipitation technique for quick (10 mins) precipitation of AuNPs. The fluorescence of 1 is selectively turned off, with AuNPs showing quenching of the emission peak at 515 nm. In the presence of large varieties of competing analytes, the performance of 1 remained intact. The interaction with 1 has resulted in the precipitation of AuNPs as an adduct 1-AuNPs. The latter has been used as the precursor for ICP-MS-based validation without any requirement of pre-concentration. Actual samples analysis showed an accuracy of > 95%, indicating the practical applicability of the present method for estimating AuNPs present in nanowaste.