Discrimination of the Coptis chinensis geographic origins with surface enhanced Raman scattering spectroscopy

In this paper, we have developed a novel method which can identify the geographic origins of the Coptis chinensis using the surface enhanced Raman scattering spectroscopy (SERS) without requiring the strict separation and complex preprocessing. The main characteristic Raman peaks information can be employed to distinguish the Coptis chinensis from different origins. The unsupervised exploratory analysis principal component analysis (PCA) is applied to raw SERS spectra as well as the SERS spectra treated with the improved asymmetric least squares (IAsLS) baseline correction method. The supervised DPLS model is employed to validate the discrimination of Coptis chinensis origins. The results indicate that the main characteristic Raman peaks information of Coptis chinensis, which is consistent with the liquid chromatography analysis results, is different from their geographic origins. Moreover, PCA and DPLS score plots results further depict SERS spectroscopy can be applied to discriminate the origins of Coptis chinensis. Therefore, SERS spectroscopy is a suitable method for identifying the origins upon the berberine content in Coptis chinensis as well as many other detection applications.