核磁共振氢谱测定盐酸浓度的探讨

Studies on H-NMR for the Determination of HCl Concentrations

探讨了用核磁共振氢谱检测盐酸浓度的方法。使用简易核磁共振氢谱直接检测无氘代溶剂参与的HCl溶液,通过合适的锁场、匀场及参数设置,能获得满意的氢谱。对系列已知浓度的HCl溶液进行检测,以含1,4-二氧六环的毛细管内标做参比,得到化学位移在7.99ppm(浓HCl)至4.67ppm(纯水)之间,作图获得标准曲线,化学位移与HCl浓度呈良好的线性关系。应用标准曲线对HCl的挥发度进行探讨,动力学实验显示在50℃与25℃时,浓HCl分别在7d与25d达到稳定的浓度,约为7mol·L-1。

The studies on H-NMR for the determination of HCl concentrations were conducted.Facile H-NMR detection was developed to measure the proton spectra of HCl directly in the absence of solvent.Satisfactory spectra were obtained with reasonable lock,shim and parameters setup.Internal capillary tube containing 1,4-dioxane was used as standard for chemical shift calibration.The concentration of HCl of 12 mol·L^-1 and0mol·L^-1（pure water）was detected as 7.99 and 4.67 ppm,respectively.Standard curve of concentrations versus chemical shifts was obtained with excellent linearity.By applying the standard curve,kinetic experiments of the evaporation rate of HCl were conducted and the results showed that it took 7and 25 days,respectively,for the concentrated HCl to reach around 7mol·L^-1 at 50℃ and 25℃.