红外光谱法用于安钠咖中咖啡因和苯甲酸钠快速定性和定量分析

Rapid Qualitative and Quantitative Analysis of Caffeine and Sodium Benzoate in Annaca by Infrared Spectroscopy

目的建立安钠咖样品中咖啡因和苯甲酸钠快速定性和定量分析的红外光谱方法。方法采用高纯度咖啡因和苯甲酸钠混合制样的方法制备定性和定量建模样品,通过分析混合样品的红外光谱图,确定安钠咖样品中咖啡因和苯甲酸钠的特征吸收峰。采用偏最小二乘法(partial least squares,PLS)建立红外光谱定量模型。结果通过分析17个咖啡因和苯甲酸钠混合样品(咖啡因纯度范围10%~80%)的红外光谱图,确定了咖啡因的特征吸收峰为1698、1650、1237、972、743、609cm-1;苯甲酸钠的特征吸收峰为1596、1548、1406、845、708、679cm-1。将所有特征吸收峰均检出作为阳性判断依据时,48个安钠咖缴获样品中咖啡因和苯甲酸钠的阳性检出率均为100%。咖啡因PLS定量模型的线性范围为10%~80%,决定系数(R2)为99.9%,交叉验证均方差(root mean square error of cross validation,RMSECV)为0.68%,预测均方差(root mean square error of prediction,RMSEP)为0.91%;苯甲酸钠PLS定量模型的线性范围为20%~90%,R2为99.9%,RMSECV为0.91%,RMSEP为1.11%。配对样本t检验结果显示,高效液相色谱法和红外光谱法的测定结果差异无统计学意义。采用所建立的红外定量方法分析48个安钠咖缴获样品,咖啡因的纯度为27.6%~63.1%,苯甲酸钠的纯度为36.9%~72.3%。结论采用红外光谱法对安钠咖样品中的咖啡因和苯甲酸钠进行快速定性和定量分析,可提高检验鉴定效率、降低检验成本。

Objective To establish an infrared spectroscopic method for the rapid qualitative and quantitative analysis of caffeine and sodium benzoate in Annaka samples.Methods Qualitative and quantitative modeling samples were prepared by mixing high-purity caffeine and sodium benzoate.The characteristic absorption peaks of caffeine and sodium benzoate in Annaka samples were determined by analyzing the infrared spectra of the mixed samples.The quantitative model of infrared spectra was established by partial least squares(PLS).Results By analyzing the infrared spectra of 17 mixed samples of caffeine and sodium benzoate(the purity of caffeine ranges from 10% to 80%),the characteristic absorption peaks for caffeine were determined to be 1698,1650,1237,972,743,and 609 cm^(-1).The characteristic absorption peaks for sodium benzoate were 1596,1548,1406,845,708 and 679 cm^(-1).When the detection of all characteristic absorption peaks was the positive identification criteria,the positive detection rate of caffeine and sodium benzoate in 48 seized Annaka samples was 100%.The linear range of PLS quantitative model for caffeine was 10%-80%,the coefficient of determination(R2)was 99.9%,the root mean square error of cross validation(RMSECV)was 0.68%,and the root mean square error of prediction(RMSEP)was 0.91%;the linear range of PLS quantitative model for sodium benzoate was 20%-90%,the R2 was 99.9%,the RMSECV was 0.91% and the RMSEP was 1.11%.The results of paired sample t test showed that the differences between the results of high performance liquid chromatography method and infrared spectroscopy method had no statistical significance.The established infrared quantitative method was used to analyze 48 seized Annaka samples,the purity of caffeine was 27.6%-63.1%,and that of sodium benzoate was 36.9%-72.3%.Conclusion The rapid qualitative and quantitative analysis of caffeine and sodium benzoate in Annaka samples by infrared spectroscopy method could improve identification efficiency and reduce determination cost.