In-situ formation of ion-association nanoparticles induced enhancements of resonance Rayleigh scattering intensities for quantitative analysis of trace Hg2 + ions in environmental samples

•The formation of (TP)2(HgI4) ion-association nanoparticles was discussed.•Ion-association nanoparticles contribute to the development of RRS technique.•Trace determination of Hg2 + was achieved using a novel RRS method.•The developed method was used to environmental analysis with great results.

In this paper, Hg2 + ions are demonstrated to form anionic [HgI4]2 − complexes after interacting with massive amount of I− ions. Subsequently, the addition of tetradecyl pyridyl bromide (TPB) can make [HgI4]2 − anionic complexes react with univalent tetradecyl pyridyl cationic ions (TP+), forming dispersed ion-association complexes (TP)2(HgI4). Due to the extrusion action of water and Van der Waals force, the hydrophobic ion-association complexes aggregate together, forming dispersed nanoparticles with an average size of about 8.5 nm. Meanwhile, resonance Rayleigh scattering (RRS) intensity is apparently enhanced due to the formation of (TP)2(HgI4) ion-association nanoparticles, contributing to a novel technique for Hg2 + detection. The wavelength of 365 nm is chosen as a detection wavelength and several conditions affecting the RRS responses of Hg2 + are optimized. Under the optimum condition, the developed method is used for the determination of Hg2 + in aqueous solution and the detection limit is estimated to be 0.8 ng mL− 1. Finally, the practical application of the developed method can be confirmed through the detections of Hg2 + in waste and river water samples with satisfactory results.

Graphical abstractA novel assay for the detection of Hg2 + in environmental sample based on the enhanced resonance Rayleigh scattering spectrum.Figure optionsDownload full-size imageDownload as PowerPoint slide