硫化钠表面增强拉曼光谱及其在味精检测中的应用研究

采用表面增强拉曼光谱(SERS)表征了硫化钠分子的振动模式，获得了硫化钠较为全面的分子结构振动信息，确定以472 cm-1的特征峰为研究对象。以金溶胶为表面增强活性基底，研究了金纳米粒子粒径对增强效果的影响，确定粒径为97 nm的金溶胶增强效果最佳。以硝酸作为促凝剂，测得不同浓度硫化钠溶液的SERS。结果表明，当硫化钠浓度低至10-6 g·mL-1时，依然可以得到明显的拉曼光谱信号，光谱强度与金溶胶和硫化钠溶液的配比有关。将这种硫化钠的检测方法应用于味精样品的检测之中。分别在不同浓度的10 mL硫化钠溶液中溶入1 g味精，检测所得溶液的SERS。结果表明，当每千克味精中硫化钠的含量为10 mg时仍可检测出SERS信号，此种方法无需样品的预处理，操作简便快捷，在味精中硫化钠的定性检测方面具有特有的优势。

Research on the Surface-Enhanced Raman Spectrum of Sodium Sulfide Nonahydrate and Its Application in Monosodium Glutamate Detecting

The surface-enhanced Raman spectrum of sodium sulfide was studied and the structure vibration information was obtained. The raman characteristic peak at 472 cm-1 was selected to evaluate enhanced effects. Gold colloid was used as active substrate, The relationship between gold nanoparticle size and enhanced efficiency was analysised and the optimum size for SERS is 97 nm. The surface enhanced Raman scattering spectra of sodium sulfide at different concentrations were also presented. The results indicated that SERS spectra of sodium sulfide can be found even the concentration reach 10-6 g·mL-1. The performance of active substrate is related with the ratio of sample and gold colloid. In the real situation, 1 g monosodium glutamate was added to 10mL sodium sulfide solution with different concentration and then SERS spectra of these samples were collected respectively. The lever of qualitative detection can reach 10mg·kg-1. And due to the simple procedure in sample preparation, this method is of great potential in on-line qualitative detection.