Rapid Quantification of Flavonoids in Propolis and Previous Study for Classification of Propolis from Different Origins by Using Near Infrared Spectroscopy 

A fast, simple and accurate near infrared spectroscopy (NIRs) method was investigated for the geographical origin discrimination and main flavonoids content determination of Chinese propolis.

150 samples from four provinces of China were collected for establishing partial least squares (PLS) models of rutin, myricetin, quercetin, kaempferol, apigenin, izapinin, pinocembrin, chrysin, galangin and total flavonoids. The root mean square error of prediction (RMSEP) and correlation coefficient (R2) in test set of the optimum models were 0.479 to 1.332 and 76.23 to 96.68. The residual prediction deviation (RPD) were all larger than 2.93. A paired T-test result showed that there was no significant difference between NIR and HPLC method at 95% confidence interval. A principal component analysis (PCA)-Mahalanobis distance (MD) method was applied to classify the geographical origin of propolis samples, and 100% accuracy was obtained.

Finally, an quality assessment was performed, and the propolis samples from Zhejiang and Liaoning province were classified good quality.

The developed NIRs method was a suitable tool for the rapid analysis of Chinese propolis, and might be also extended in the on-line quality control of propolis raw material in pharmaceutical industries, or monitoring industrial natural products extracting processes.