基于水内标的NO^(-)_(3),SO^(2-)_(4),ClO^(-)_(4)拉曼光谱定量分析研究  

Quantitative Analysis of NO^(-)_(3),SO^(2-)_(4),ClO^(-)_(4)With Water as Internal Standard by Raman Spectroscopy

作　　者：王淦麟 柳倩 李定明[1] 杨素亮[1] 田国新[1,2] WANG Gan-lin;LIU Qian;LI Ding-ming;YANG Su-liang;TIAN Guo-xin(Department of Radiochemistry,China Institute of Atomic Energy,Beijing 102413,China;Institute of Nuclear and New Energy Technology,Tsinghua University,Beijing 100084,China)

机构地区：[1]中国原子能科学研究院放射化学研究所,北京102413 [2]清华大学核能与新能源研究院,北京100084

出　　处：《光谱学与光谱分析》2022年第6期1855-1861,共7页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(ED17001203),稳定基础科研计划项目资助。

摘　　要：拉曼光谱由于重现性差,在进行定量分析时往往需要内标。在水溶液中,水在2700~3900 cm^(-1)范围伸缩振动拉曼峰很强,有作为内标的可能性,但水与溶质的相互作用会导致水伸缩振动拉曼峰形状发生变化,此外水的占比也会随着溶质浓度的变化而变化,当溶质浓度较高时需要对水的含量进行校正。将这两点因素考虑在内,研究了以水为内标,采用拉曼光谱法测量水溶液中NO^(-)_(3),SO^(2-)_(4)和ClO^(-)_(4)浓度的适用性。不同浓度NaNO_(3),Na_(2)SO_(4)和NaClO_(4)溶液的拉曼光谱显示随着盐浓度的升高水在2700~3900 cm^(-1)范围内的拉曼峰呈现出左肩下降右肩上升的变化趋势。将三种盐溶液拉曼光谱中酸根离子拉曼峰面积(A_(盐))和水的拉曼峰面积(A H_(2)O)的比值(R^(S)=A_(盐)/A H_(2)O)与溶液中酸根离子和水的含量的比值(c_(盐)/c H_(2)O)作图,均呈现出良好的线性关系,拟合得到三条相关曲线的R^(2)分别为0.9991,0.9991和0.9994,说明酸根离子和水的拉曼散射系数均未发生变化或者在同比例变化。虽然水拉曼峰的形状发生了改变,但并不会影响水作为内标的可行性。在引入水的含量修正后,经理论推导c_(盐)与R^(S)符合关系式:c_(盐)=AR^(S)/(1+BR^(S))。在0.1 mol·L^(-1)到近饱和的宽浓度范围内,将R^(S)对c_(盐)作图,通过数据拟合获得的NaNO_(3),Na_(2)SO_(4)和NaClO_(4)的工作曲线分别为c NaNO_(3)=18.8 R^(S)/(1+0.6 R^(S))(R^(2)=0.9991),c Na_(2)SO_(4)=20.2 R^(S)/(1+1.0 R^(S))(R^(2)=0.9988),c NaClO_(4)=15.0 R^(S)/(1+0.7 R^(S))(R^(2)=0.9998)。NaNO_(3),Na_(2)SO_(4)和NaClO_(4)的检出限分别为0.0080,0.0052和0.0073 mol·L^(-1)。在水拉曼峰形状变化不影响其作内标可行性的基础上,当溶液中同时存在两种阴离子时,通过在水含量修正部分加入干扰离子对水含量的影响,可以在单盐溶液定量工作曲线中加入校正项来消除溶液中干扰离子对待测离子分析结果的干扰,但当干�Internal standard is often required when using Raman spectroscopy for quantitative analysis due to the poor reproducibility of the Raman spectrum.In aqueous solutions,the stretching vibration Raman peak of water at 2700~3900 cm^(-1)has a strong intensity and may be used as an internal standard,but the interaction of water and solute will cause the shape of the water stretching vibration Raman peak to change.In addition,the concentration of water will also change with the change the solute concentration.When the solute concentration is high,the water concentration needs to be corrected.Taking these two factors into consideration,quantitative analyses of NO^(-)_(3),SO^(2-)_(4),ClO^(-)_(4)in aqueous solutions with Raman spectroscopy are investigated,focusing on evaluating water as an internal standard.The Raman spectra of different concentrations of NaNO_(3),Na_(2)SO_(4),NaClO_(4)solutions show that with the increase of salt concentration,the Raman peak of water in the range of 2700~3900 cm^(-1)presents a trend that the left shoulder drops and the right shoulder rise.However,there exists a good linear relationship between A_(salt)/A H_(2)O and c_(salt)/c H_(2)O in NaNO_(3),Na_(2)SO_(4),NaClO_(4)solutions,where A represents the area of the Raman peak and c represents the concentration,and the R^(2)of the three fitting curves are 0.9991,0.9991,0.9994,respectively.This indicates that the Raman scattering coefficients of acid ions and water do not change or change in the same proportion.So,although the shape of the water Raman peak having changed,the feasibility of water as an internal standard is not affected.After introducing the correction of the concentration of water,it is theoretically deduced that c_(salt) and conform to the relationship:c_(salt)=AR^(S)/(1+BR^(S)),where R^(S)=A_(salt)/A H_(2)O.In a wide concentration range from 0.1 mol·L^(-1)to near saturation,the standard working curves for NaNO_(3),Na_(2)SO_(4),and NaClO_(4)are obtained to be c NaNO_(3)=18.8 R^(S)/(1+0.6 R^(S))(R^(2)=0.9991),c Na_(2)SO_(4)=20.

关 键 词：水内标 拉曼光谱 NO^(-)_(3) SO^(2-)_(4) ClO^(-)_(4) 定量分析 

分 类 号：O657.37[理学—分析化学]