Application Of Surface-Enhanced Raman Spectroscopy To Determination Of Mercury And Fonofos

The Raman spectroscopy is an important method for researching the structure ofthe molecules. The normal Raman signals are weak, which limits the developmentand application of the Raman spectroscopy, especially in quantitative analysis.Surface-enhanced Raman spectroscopy （SERS） is an exceptionally analytical methodfor its high sensitivity and identification about the chemical structures. Recently,SERS spectroscopy has been developed as a potential method and is widely appliedfor detecting single molecule in chemistry, biology and medicine. In the thesis, thecolloid nanoparticles were used as substrates and Hg²⁺in the environmental water andfonofos in vegetable were determined by SERS.Silver colloid modified with sodium2-mercaptoethanesulfonate （mesna） exhibitstrong SERS signal. Their specific and strong interaction with heavy metal ions led toa label-free assay of Hg（II）. The Raman peak at795cm^-1can be used forquantification. The effect of the concentration of mesna, the concentration of sodiumchloride, incubation time and pH value on SERS signal were examined. Under theoptimal conditions, the intensity of SERS decreases with increasing concentration ofHg（II）. The decrease is linear in the Hg（II） concentration range of0.01to2.0μmol L^-1with a correlation coefficient （r） of0.998and detection limit （S/N=3） is0.0024μmolL^-1. The method was successfully applied to the determination of the Hg（II） in spikedwater samples with satisfactory results.Gold colloid was used as SERS substrate to determine fonofos. In order toachieve the optimal SERS signals, the effect of adding order of reagents, sodiumchloride concentration, incubation time and pH value were examined. Under the optimum conditions, the SERS intensity is proportional to the concentration offonofos in the range of5.0to100.0μg L^-1. The corresponding correlation coefficientof the linear equation is0.992. The real samples were analyzed and the RSDs arelower than the3.8%. The recoveries of the fonofos in the three vegetables are between62.5%and92.0%, which indicates that the present method is believable andsatisfactory.