近红外光谱法测定茶多酚中总儿茶素含量

以高效液相色谱(HPLC)分析结果为参考值,建立了快速测量茶多酚中总儿茶素含量的近红外光谱定标模型.将48份茶多酚样品组成定标样品集,在1000～2500nm(4000～10000cm-1)的近红外漫反射光谱为定标波长范围内,光谱经一阶导数(Firstderivative)、二阶导数(Secondderivative)、标准归一化(Stan-dardnormalvariate,SNV)和多元散射校正(multiplicativesignalcorrection,MSC)处理后结合偏最小二乘回归(PLS)定标.经内部交叉验证表明,光谱经SNV处理后建模结果最佳.模型的相关系数Corr.Coeff=0.997,校正均方根RMSEC=1.71%.比较了经典最小二乘法(CLS)、偏最小二乘法(PLS)和主成分回归(PCR)等方法建模结果,以偏最小二乘回归建模效果最好.

Feasibility study on quantitative analysis of total catechins in tea polyphenol powder by near-infrared spectroscopy

This paper indicates the possibility to use near infrared spectroscopy (NIRS) combined with PLS as a rapid method to determine the content of total catechins in tea polyphenol (TP) powder. Reference values of total catechins of 48 TP powder samples were analyzed by HPLC. PLS calibration models were built with diffuse reflectance spectra in 1 000~2 500 nm region after pre-processed with first derivative, second derivative, standard normal variate (SNV), and multiplicative signal correction (MSC) respectively. Results indicated that the calibration model built with PLS after spectra pre-processed with SNV was the best. The correlation coefficient and RMSEC of this model were 0.997 and 1.71 % respectively. The comparison of the calibration models built with CLS, PLS and PCR indicated that the PLS was the optimal method.