On-site detection of As

A portable and simple method was developed for on-site selective determination of As(III) based on the SERS signal of As(III)-O vibration. The method relies on the synergistic effect of nanoparticles aggregation and analyte adsorption. Experimental results demonstrated that phosphate replaced the ligands of HH@Ag NPs, which in turn facilitated the adsorption of As(III) on the surface of HH@Ag NPs. The phosphate was introduced as an agglomerating agent to improve the detection ability of the method for As(III). The method shows good selectivity and linear relationship between 5 x 10.sup.-8 and 0.8 x 10.sup.-6 M, with the detection limit of 1.8 x 10.sup.-9 M. The method was applied to actual water samples and successfully detected As(III), indicating that the method could have application potential in actual detection scenarios. Graphical abstract