Direct analysis of traditional Chinese medicines using Surface-Enhanced Raman Scattering (SERS). Surface-Enhanced Raman Scattering (SERS) spectrometry provides an excellent tool to characterize chemical constituents in Traditional Chinese Medicines (TCMs) without requiring separation and extraction procedures. 
Surface-Enhanced Raman Scattering (SERS)
Density functional theory (DFT) was used to calculate the expected Raman spectrum of berberine, and liquid chromatography- mass spectrometry (LC-MS) was used as a comparative technique to quantify the amount of berberine in the samples. 
Density functional theory (DFT)