采用表面增强拉曼光谱技术快速分析白酒中非法添加物糖精钠甜味剂。 以金溶胶为增强基底, 对金溶胶、 待测溶液与氯化钠溶液体积比、 混合时间和测定体系pH值试验条件进行优化。 结果表明, 当待测溶液、 增强基底和氯化钠溶液体积比为1∶1∶0.5、 混合时间为5 min、 pH值为4时, 获得的拉曼信号最好。 结合密度泛函理论, 对糖精钠分子进行谱峰归属, 确定了定性定量分析白酒中糖精钠的3个特征谱峰: 1 148, 1 164和1 296 cm-1。 以特征峰1 164 cm-1的峰强度与白酒中糖精钠浓度建立线性方程, 该方程在1~20 mg·L-1浓度范围内线性关系良好, R2决定系数为0.993 3, 方法回收率在98.57%~102.5%之间, 相对标准偏差(RSD)在2.44%~8.6%之间。 此方法分析白酒中糖精钠的最低检出浓度可达到1 mg·L-1, 单个样本检测时间在10 min内完成。 研究表明, 采用表面增强拉曼光谱方法能快速准确分析白酒中的糖精钠甜味剂, 可为白酒中甜味剂实时快速检测装置开发提供方法支持。

In this paper, surface enhanced Raman spectroscopy (SERS) was employed to realize quick detection of illegally additive (sodium saccharin sweeteners) in spirit. Gold colloid was used to enhance Raman signal of molecule. Several parameters such as the volume ratio of gold colloid, detection sample and sodium chloride solution, time of mixing, pH value of working buffer were optimized. The results illustrated that the strength of Raman signal was maximum when the volume ratio of gold colloid, detection sample and sodium chloride solution, time of mixing, pH value of working buffer were 1∶1∶0.5, 5 min and 4, respectively. Contrasting the test values of sodium saccharin sweeteners and the simulation values with Density Functional Theory, and three characteristic peaks of sodium saccharin sweeteners such as 1 148, 1 164 and 1 296 cm-1 were found. These characteristic peaks could be as a basis for qualitatively and quantitatively analyzing sodium saccharin sweeteners in spirit. The standard curve of saccharin sodium concentration in spirit was established based on the strength of 1 164 cm-1. The results indicated that the curve possessed a good linear relationship within the range of 1 and 20 mg·L-1, and the determination coefficient was 0.993 3. Average recovery of saccharin sodium in spirit was 98.57%~102.5%, and the relative standard deviation (RSD) was 2.44%~8.6%. The minimum detectable concentration of sodium saccharin sweeteners in spirit reached to 1 mg·L-1 and the detection time of a sample was within 10 min. The study indicated that SERS method could rapidly and accurately identify saccharin sodium sweeteners in spirit. This study can offer a method as a support for the development of real-time and rapid detection device in liquor.