Study on origin traceability of amur cork-tree bark based on stable isotopes and multielements combined chemometrics

Abstract

Amur cork-tree bark is a natural medicine in China with a large market, whereas confusion about its origin limits its cultivation and commercial value. To trace the origin, the stable isotope ratios (δ13C, δ15N, δ2H, and δ18O) and multiple elements (As, Hg, Al, Ca, Fe, K, Mg, Na, Cr, Cd, Pb, Be, Cu, Zn, Sr, and Ba) of 83 batches of Amur cork-tree bark samples from 7 habitats were determined by stable isotope mass spectrometry and inductively coupled plasmamass spectrometry. The results showed that the two-dimensional combination of δ13C and δ15N in the scatter diagram of stable isotopes could obviously distinguish Amur cork-tree bark from Sichuan Province from other producing areas, and multielement radar map analysis could also be used to distinguish Amur cork-tree bark from different geographical sources. In this article, the data of stable isotope ratios and multielement content were combined for principal component analysis (PCA), linear discriminant analysis (LDA) and orthogonal partial least square discriminant analysis (OPLS-DA). The results of principal component analysis showed that all samples could be preliminarily distinguished. The prediction model established and verified by linear discriminant analysis realized 100% accurate classification for known samples. The correct rate of analysis and prediction for unknown samples was 94.5%. The effective feature discriminant markers of Amur cork-tree bark caused by VIP > 1 (Ca, K, Pb, Mg, Cr, As) were found by orthogonal partial least square discriminant analysis. It could accurately identify Amur cork-tree bark from different producing areas.