Detection of Soluble Mercury in Cinnabar Using a CV-Ag NPs SERS Probe

In the current work a uniform morphological Ag nanoparticles (Ag NPs) were prepared with ascorbic acid as a reducing agent and citrate as a stabilizer. The surface of Ag NPs modified by crystal violet (CV) and potassium iodide (KI) was used as an aggregation agent to obtain CV modified Ag NPs (CV-Ag NPs) probes for detecting mercury ions. The mercury ions could be reduced to mercury molecules by citrate, and then deposited on the surface of Ag NPs, leading to the separation of CV molecules from the surface of Ag NPs. Therefore, the SERS signal intensity of CV decreased with the increase of the Hg²⁺ concentration and the concentration of Hg²⁺ was in the range of 1 × 10^-11 to 1 × 10^-5 M. Taking the change of the characteristic peak intensity of CV at 913 cm^-1 as a reference, the SERS spectrum intensity of CV has a linear relationship with the Hg²⁺ concentration. The equation is y = -333.55x + 1343.05, where the linear correlation coefficient is R² = 0.980, and the recovery rate is between 84.20 to 105.60%. Finally, the CV-Ag NPs probe was used to quickly detect soluble mercury in cinnabar. Compared with the conventional large-scale instrument detection method, this simple and fast method, can be applied for rapid detection of soluble mercury, and has a certain significance for concerning the research of mineral medicine processing mechanism.