| In this paper,the main content was to fabricate nano-silver particles with three different morphologies and study its Surface-enhanced Raman scatting?SERS?applications.The effects of different experimental parameters on the prepared nano-silver particles were studied,and the experimental parameters were optimized to obtain a better SERS enhancement effect.These well-prepared nano-silver particles was used as SERS substrates for quantitative detection and analysis.The details are shown as following:1.The star-shaped nano-silver particles was prepared.The effects of different silver nitrate?AgNO3?concentration,HA amount and reaction time on the morphology of silver nanoparticles were investigated.The morphology of the nano-silver particles was characterized by SEM.The optimal preparation program of the star-shaped nano-silver particles was determined:0.5 mL HA(6×10-2mol/L),0.5 mL sodium hydroxide?NaOH?solution?5×10-22 mol/L?,9 mL AgNO3(10-3mol/L),0.1 mL trisodium citrate solution?4.13×10-22 mol/L?,the reaction time is6 h.The detection limit for R6G was 10-9mol/L.2.The cubic nano-silver particles was prepared,and the effect of reaction time,sodium sulfide?Na2S?concentration and reaction temperature on its morphology was studied.The morphology of cubic nano-silver particles was characterized by SEM,and size distribution were analyzed by UV-vis absorption spectroscopy.The optimal preparation program of the cubic nano-silver particles was determined:the reaction time was 1h,the reaction temperature was 135°C,10 mL Na2S ethylene glycol solution?50?mol/L?,polyvinylpyrrolidone?PVP?0.167 g,10 mL AgNO3ethylene glycol solution?0.1 mol/L?.By SERS characterization,it was found that the detection limit for R6G was 10-9mol/L.3.By the liquid phase reduction method,the flower-shaped nano-silver particles with different diameters,different surface roughness and different numbers of“hot spots”was obtained by changing the amount of AgNO3.By means of SEM characterization and SERS test,the flower-shaped nano-silver particles with the largest surface protrusion,the largest roughness and the most“hot spots”was selected.The diameter was about 500 nm.The prepared flower-shaped nano-silver particles were deposited on the filter paper and silicon wafer respectively.The effect of NaCl concentration on the adsorption of the flower-like nano-silver particles on filter paper and the effect on SERS enhancement was studied.The optimum NaCl concentration was 0.3 mol/L.The sensitivity and uniformity of the silicon SERS substrate and the filter paper SERS substrate were compared.The results showed that the sensitivity and uniformity of the prepared silicon wafer SERS substrate were significantly better than the filter paper SERS substrate.The intensity RSD of the bands at 611 cm-11 and 1510 cm-11 was 8.16%and 7.14%,respectively.4.Considering the difficulty of the preparation process of nanoparticles and SERS enhancement effect,the prepared cubic nano-silver particles and flower-shaped nano-silver particles was used as SERS substrates.And SERS spectra of the same concentration of ethyl carbonate?EC?adsorbed on the two substrates were compared.The results show that the flower-like nano-silver SERS substrate is more suitable for EC analysis.Therefore,the flower-shaped silver substrates were used for recording SERS spectra of EC with gradient concentration.The detection for EC was10-99 mol/L.A linear model of EC concentration and the intensity of characteristic band was established with a correlation coefficient of 0.99 and the linear range of10-510-9mol/L.The standard discovery test was carried out with EC in white liquor solution at concentrations of 10-77 mol/L,10-88 mol/L and 10-99 mol/L.The recovery ratio was 92.9±3.85%.It is indicated that the surface-enhanced Raman spectroscopy based on flower-like nano-silver SERS substrate can be used as an effective means for quantitative detection of trace EC in alcoholic beverages and other fermented foods. |
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