Sensitivity Detection Methods Based On Localized Surface Plasmon Resonance And Electrochemical Analysis

It is an important direction of research to enhance the sensitivity of analysismethods. Through enhancing the sensitivity, we can not only analyze environmentallyharmful substances more effectively, but also promote the development of analysisequipments. In this thesis, we investigated the methods to enhance the sensitivity oflocal surface plasmon resonance and electrochemistry analysis, and applied to theanalysis of mercury and functional molecules. The main works were included asfollows:(1) We synthesized seven sizes of gold nanoparticles (AuNPs) and two sizes ofgold nanorods (AuNRs). UV-vis, TEM and SEM were used for analyzing AuNPs andAuNRs. The influences of Na3Ct to the sizes of AuNPs and AgNO3to AuNRs wereresearched. Four kinds of AuNPs and two kinds of AuNRs were chosen to detectinorganic mercury ion. Experimental parameters, including pH value of buffersolution, concentration of NaBH4and reaction time were optimized. Wavelengthdisplacement method was used to analyze mercury and the linear equations wereestablished. The sensitivities were improved when the sizes of AuNPs and AuNRswere increased. The sensitivity of AuNRs was higher than that of AuNPs. AuNRswere suitable to analyze relatively low concentration of mercury, and AuNPs weresuitable to analyze relatively high concentration of mercury.(2) We firstly prepared an electrode (PMel/Au/GCE) which was modified bygold nanoparticles (AuNPs) and polymerized film of melamine (PMel). EIS was usedfor analyzing the modified electrode. The electrochemical behavior of rutin wasinvestigated by cyclic voltammetry (CV), and a couple of sensitive and reversibleredox peaks were obtained with an oxidation peak at0.422V and a reduction peak at0.374V. It was found that the oxidation peak current (Ipa) and the reductive peak (Ipc)current at PMel/Au/GCE was obviously larger than those at GCE electrode or atPMel/GCE electrode, indicating that the sensitivity of detecting rutin was improved.Experimental parameters, including pH value of buffer solution, electro-depositedtime of AuNPs, electro-polymerized time of PMel and scan rate were optimized. Thedifferential pulse voltammetry (DPV) was used to quantitatively analyze rutin. We gottwo linear ranges, i.e. between7.8×10-9and1.2×10-6M and between1.2×10-6and1.5×10-5M. The linear equations were Ip(μA)=22.293C (μM)+19.071(R2=0.997)and Ip(μA)=0.903C (μM)+44.988(R2=0.993), and the detection limit was5.5 10-9M (S/N=3). Finally, the modified electrode was successfully used to detectrutin in rutin tables, and the recoveries were between96.4%and101.8%.(3) We firstly synthesized SBA15@hemin composite mesoporous material.TEM and FT-IR were used to analyze the material. Then, SBA15@hemin/CS/GCEelectrode was prepared. The electrochemical behavior of folic acid (FA) wasinvestigated by cyclic voltammetry (CV). It was found that the oxidation peak current(Ipa) at SBA15@hemin/CS/GCE was obviously larger than those at GCE,SBA15/CS/GC or SBA15-NH2/CS/GCE electrode, indicating that the sensitivity ofdetecting FA was improved. Experimental parameters, including pH value of buffersolution, modified volume of SBA15@hemin/CS, and scan rate were optimized. Thedifferential pulse voltammetry (DPV) was used to quantitatively analyze FA. We got alinear range from5.0×10-6to1.0×10-3M. The linear equation was Ip(μA)=0.033C(μM)+5.837(R2=0.993), and the detection limit was3.3×10-6M (S/N=3). Finally,the modified electrode was successfully used to detect FA in Folic acid tables andVegetarian tables.