A Rapid Surface-Enhanced Raman Scattering Method for the Determination of Trace Hg~(2+) Using Rhodamine 6G-Aggregated Nanosilver as Probe

摘要

In pH 6.0 Na_2HPO_4-NaH_2PO_4 buffer solution and in the presence of cetyltrimethyl ammonium bromide, nanosilver particles were aggregated to a stable suspension. Therein, rhodamine 6G (Rh6G) exhibited three strong surface-enhanced Raman scattering (SERS) peaks at 613, 1,363, and 1,510 cm~(-1), and their SERS intensities were enhanced when the concentration of Rh6G increased. In the presence of Hg~(2+), the SERS intensity decreased greatly owing to formation of stable Rh6G-HgBr_4~(2-) ternary association complex molecules as well as its particles. In the optimal condition, the decreased SERS intensity at 613 cm~(-1) responds linearly with the concentration of Hg~(2+) over 25-2,000 nmol/L. Thus, a new sensitive SERS method has been proposed for the determination of trace Hg~(2+) in the water sample, with satisfactory results.