The Research Of SERS Analytical Method For High Selectively Detecting Metal Ions

Surface-enhanced Raman scattering spectroscopy?SERS?is an efficient technique for surface analysis based on the detection of molecular vibration.By analyzing the vibration of substance adsorbed on the specific metal substrate,especially metal nanoparticles of Ag,Au and Cu,information such as the structure of the adsorbed substance can be well obtained.It is known that the electromagnetic field effect of the metal nanoparticles can amplify and analyze the vibration information to obtain a more accurate spectral signal.Based on that,the high sensitivity of surface-enhanced Raman scattering spectroscopy allows the technology to detect single-molecules and thus be used in a variety of chemical analysis.The elimination of metal ion pollution is now becoming more and more important in field of environmental pollution.In order to detect metal ions conveniently and quickly,various analytical methods have been established.Considering the advantages of Raman spectroscopy,such as its high sensitivity and simplicity,it is better to introduce such analytical method to the field of analysis of metal ions.Aiming to that,it is important to construct a suitable substrate material for SERS detection of this type.Based on the above analysis,the main point of this thesis are summarized as follows:1.An analytical method for the selective detection of Cr³⁺was constructed,based on the SERS technique which utilize specific silver nanoparticles modified with both of isonicotinic acid hydrazide?INAH?and sodium citrate?cit?.The as synthesized AgNPs were characterized by UV-vis,DLS,XPS and FT-IR.Moreover,the possibility of the modified silver nanoparticles toward the detection of Cr³⁺were investigated by Raman spectroscopy and UV-visible absorption spectroscopy,especially surface-enhanced Raman spectroscopy.The experimental results show that the aggregation of AgNPs can be achieved via the addition of Cr³⁺,thus leading to the formation of"hot spots"and the corresponding amplification of Raman signal.It was found that the enhancement of Raman spectrum exhibited a linear relationship with the concentration of ions.The detection range and detetion limit of Cr³⁺was found to be 5.0×10^-5 mol L^-1-2.0×10^-4 mol L^-1,and 2.6×10^-5 mol L^-1 respectively.In addition,such analytical method also displayed high selectivity.2.An analytical method for the selective detection of Mn²⁺was constructed,based on the SERS technique which utilize specific silver nanoparticles modified with both of 4-mercaptobenzoic acid?4-MBA?and melamine?MA?sodium citrate?cit?.The as synthesized AgNPs were characterized by UV-vis,DLS,XPS and FT-IR.Moreover,the possibility of the modified silver nanoparticles toward the detection of Mn²⁺were investigated by Raman spectroscopy and UV-visible absorption spectroscopy,especially surface-enhanced Raman spectroscopy.The experimental results show that the aggregation of AgNPs can be achieved via the addition of Mn²⁺,thus leading to the formation of"hot spots"and the corresponding amplification of Raman signal.It was found that the enhancement of Raman spectrum exhibited a linear relationship with the concentration of ions.The detection range and detetion limit of Mn²⁺was found to be 5.0×10^-5 mol L^-1-4.0×10^-4 mol L^-1,and 2.1×10^-5 mol L^-1respectively.In addition,such analytical method also displayed high selectivity.