A stable and reproducible nanosilver-aggregation-4-mercaptopyridine surface-enhanced Raman scattering probe for rapid determination of trace Hg2+

A stable nanosilver solution was prepared, using PEG10000 as stabilizer and NaBH4 as reducer. In pH 6.6 Na2HPO4–NaH2PO4 buffer solution containing PEG10000 and NaCl, the nanosilvers (AgNPs) were aggregated to form the stable nanosilver-aggregation (AgNPA) that could conjugate with 4-mercaptopyridine (MPy) to obtain an AgNPA-MPy surface-enhanced Raman scattering (SERS) probe with a strong SERS peak at 1097 cm−1. When Hg2+ concentration increased, the SERS intensity at 1097 cm−1 decreased linearly as the stable complex of [Hg(MPy)2]2+ was formed and the AgNPA particles precipitate to the bottom. The decreased SERS intensity was linear to Hg2+ concentration in the range of 50–3000 nmol/L. Based on this, a new sensitive SERS method has been proposed for the determination of trace Hg2+ in the water sample, with satisfactory results.