基于水内标的HNO_(3)、H_(2)SO_(4)、HClO_(4)拉曼光谱定量分析研究

Quantitative Analysis of HNO_(3)、H_(2)SO_(4)、HClO_(4) with Water as Internal Standard by Raman Spectroscopy

研究了以水为内标,采用拉曼光谱法测量水溶液中HNO_(3)、H_(2)SO_(4)、HClO_(4)浓度的可行性。研究发现,酸的加入会使得水在2700~3900cm-1范围内的伸缩振动拉曼峰的形状发生变化并导致水的拉曼散射系数增大。但酸浓度较低时,在对水的浓度进行修正后,可以用溶液中水在2700~3900 cm^(-1)范围内的拉曼峰为内标对几种酸进行定量分析。通过数据拟合获得的HNO_(3)、 H_(2)SO_(4)、 HClO_(4)的工作曲线分别为c(HNO_(3))=39.9RS/(1+0.6RS)(R^(2)=0.9999)、c(H_(2)SO_(4))=44.3RS/(1+2.3RS)(R^(2)=0.9994)、c(HClO_(4))=29.4RS/(1+1.1RS)(R^(2)=0.9993),其中RS=A(酸)/A(H2O),A(酸)和A(H2O)分别为酸和水的拉曼峰面积。HNO_(3)、H_(2)SO_(4)、HClO_(4)工作曲线的应用浓度范围分别为0.1~4.8 mol/L、0.1~4.1 mol/L、0.1~6.5 mol/L,检出限分别为0.0056、0.0061、0.0086 mol/L。

Quantitative analyses of HNO_(3), H_(2)SO_(4), HClO_(4) in aqueous solutions with Raman spectroscopy are investigated with focus on evaluating water as internal standard. It is found that the Raman peak shape of water varies with the change of the concentration of acid, and the Raman scattering factor of water increases with the addition of acid. However, the Raman peak of the water in the solution in the range of 2700~3900 cm^(-1) can be used as internal standard to quantitatively analyze the acid when the acid concentration is low. With water concentration correction, the standard working curves for HNO_(3), H_(2)SO_(4) and HClO_(4) are obtained to be c(HNO_(3))=39.9 RS/(1+0.6 RS)(R^(2)=0.9999), c(H_(2)SO_(4))=44.3 RS/(1+2.3 RS)(R^(2)=0.9994), c(HClO_(4))=29.4 RS/(1+1.1 RS)(R^(2)=0.9993), respectively, where RS = A(acid)/A(H2O) and A represents the area of the Raman peak. The application ranges of HNO_(3), H_(2)SO_(4), HClO_(4) working curves are 0.1~4.8 mol/L, 0.1~4.1 mol/L, 0.1~6.5 mol/L, respectively and the limit of detection(LOD) of HNO_(3), H_(2)SO_(4), HClO_(4) are found to be 0.0056, 0.0061, 0.0086 mol/L.