拉曼光谱法快速测定矿物药石膏中二水硫酸钙的含量

Rapid determination of calcium sulfate dihydrate in mineral gypsum by Raman spectroscopy

目的:建立一种用拉曼光谱技术快速测定石膏中二水硫酸钙含量的方法。方法:首先以硝酸钠作为内标,氯化钠作为填充剂,与石膏样品混合研磨均匀,在室温干燥条件下,压片,然后进行拉曼光谱测定。测定条件:激发波长780 nm,激光功率24 mW,光阑50μm slit,10倍物镜,曝光时间2 s,累积2次,扫描范围300-1700 cm^(-1)。结果:二水硫酸钙质量分数在5%-35%范围内与二水硫酸钙和硝酸钠的拉曼特征峰强度比值(I_(1007)/I_(1068))呈良好的线性关系,线性回归方程为Y=0.019X-0.0355,R^(2)=0.9994;低、中、高3个浓度的平均加样回收率分别为99.4%、97.9%、99.1%,RSD分别为1.5%、1.1%、1.3%;10个批次石膏的二水硫酸钙含量测定结果(97.8%-102.0%)与EDTA-2Na滴定法测定结果(98.8%-101.3%)经t检验无明显统计学差异(P=0.415,>0.05)。结论:本实验建立的拉曼光谱法操作简便快速,测得的石膏样品中二水硫酸钙含量准确,可以作为药用石膏质量控制的分析方法。

Objective:To establish a Raman spectroscopic method for rapid determining the content of calcium sulfate dihydrate in gypsum.Methods:Sodium nitrate as internal standard and sodium chloride as filler were first mixed with gypsum,which were grinded,compressed into tablets and analyzed by Raman spectrometer.Analytical conditions were as follows:the excitation wavelength was 780 nm,the laser power was 24 mW,the aperture was 50μm slit,the lens was 10×objective,the exposure time was 2 s,the accumulation was 2 times,and the scanning range was 300~1700 cm^(-1).Results:The peak intensity ratio(I_(1007)/I_(1068))was used for the quantitative evaluation of the gypsum level and showed a good linear relationship with mass fraction of calcium sulfate dihydrate in the range of 5%-35%.The linear regression equation was Y=0.019X-0.0355,R^(2)=0.9994.The average recoveries at low,medium and high concentrations were 99.4%,97.9%and 99.1%,with RSD of 1.5%,1.1%and 1.3%,respectively.There was no significant difference between the analytical results(97.8%-102.0%)and those(98.8%-101.3%)with EDTA-2Na titration method by t test(P=0.415,>0.05).Conclusion:The method is rapid and accurate.It can be used as a new analytical method for quality control of medicinal gypsum.