Detection of trace mercury ions in water by a novel Raman probe

Abstract

The convenient chemical method for sensing mercury ion (Hg2+) has drawn significant attention in recent researches. Herein we report a simple, ultrasensitive and inexpensive protocol to detect trace mercury ions in water without complicatedly tagging, based on the facile synthesis of a nanocomposition, which is constructed with inositol hexaphosphate (IP6) stabilized gold nanoparticles (Au NPs) modified by crystal violet (CV) as Raman signal molecule and tri-sodium citrate (TC) as reducer, shortly named CV/TC/IP6/Au NPs. A possible mechanism for the Raman probe is the decreasing intensity of SERS band at 1173cm−1 of crystal violet (CV) with Hg2+ addition due to the reduction of Hg2+ by TC to Hg atom whose competition with CV molecules at the IP6/Au NPs surface, resulting in CV molecules detachment from the surface. The proposal Raman probe shows an unprecedented limit of detection (LOD) of 0.5pM for Hg2+. This SERS-based method of Hg2+ determination could be expected to have wide-range applications in many areas such as analysis of trace Hg2+ in river water.