| Surface-enhanced Raman scattering(SERS)spectroscopy is an important method for researching surface chemistry,surface reaction,structural characterization and nanoscience,it has solved some problems such as the weak signal of Raman scattering and the low analytical sensitivity and so on.Because of it can save much time,easy to operate and its high sensitivity,SERS has become a mean of quantitative analysis.For electrochemical methods are not only can provide microcosmic information of several of electrochemical system,but also have an enrichment of measuring materials.Therefore,combine the SERS technique with electrochemical,not merely can identify all kinds of intermediates accurately produced in electrochemical reaction process and interpret the electrochemical reaction mechanism,for the quantitative analysis,it also can future improve the sensitivity.2-picolinic acid is the metabolite of L-tryptophan,it can chelate with iron and zinc.In industry,2-picolinic acid is key intermediate in the organic reactions.So the fundamental research of 2-picolinic acid is very important and very significant for bochemical system of organic industry.And it is very necessary to build an analysis method for 2-picolinic acid.There have some reports about quantitative analysis with SERS.Adopt the hyphenated technique of electrochemical and SERS as the main research tool,the rhodamine B and 2-picolinic acid as the research objects.The major research contents are as follows:The electrochemical behavior of rhodamine B on the glassy carbon electrode had been studied by using cyclic voltammetry techniques,and then researched the influence of electrolyte,scanning speed and pH on the potential of reduction peak,the peak current and the number of reduction peaks of rhodamine B.The results showed that the electrolytes can improve the current of rhodamine B obviously;A linear relationship holds between the scanning speed and potential or current of the reduction peaks when the scanning speed is 50-300 mV/s;The pH has a great influence on the on the potential of reduction peak,the peak current and the number of reduction peaks of rhodamine B.The number of reduction peaks are increased with the increasing of pH,there is only one peak when the pH is from 1?3,two peaks when the pH reached 5,the third peak would appeared when the pH reached 9.The currents were increased first and decreased afterwards as the pH increased.The potentials have a negative shift as the pH increased.The electrochemical reaction mechanism and the spatial configuration of dimmers of rhodamine B on the glassy carbon electrode had been discussed.Results indicate that the spatial configuration of dimmers of rhodamine B in solution' polymerization method is "head-to-head stack" of the xanthene groups with the benzoate rings oriented "outward";The electrode reaction belongs to irreversible reduction reaction,the H+ and electrons were participate in this reaction with the ratio of 1:1.The SERS spectral properties of 2-picolinic acid on rough silver surface had been studied in different conditions.The pH determine the existing form of 2-picolinic acid in the solution and the Raman intensity reaches the maximum at 4.00,it will be unstable while the pH too high or too low.The adsortption orientation of 2-picolinic acid would be change at different electrode potential;In addition,the trends of SERS signal of 2-picolinic acid were not consistent with the adsorption time at the different electrode potential.The SERS signal of 2-picolinic acid would be inhibited by common anions,with the effectiveness in descending order:ClO4-<SO42-<Cl-<Br-<r.The conditions of electrochemical-surface-enhanced Raman scattering quantitative analysis of 2-picolinic acid were optimized,the methodology evaluation was performed for this method and the influences of halide ions were observed. |
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