ObjectiveThis study aimed to establish the multi-technique characteristic profiles of the traditional Chinese medicine Alumen. By using X-ray diffraction （XRD）， Fourier-transform infrared spectroscopy （FTIR）， and thermogravimetric-differential thermal analysis （TG-DTA）， and explore the spectral characteristics for rapid identification of Alumen and its potential adulterant， Ammonium alum.MethodsA total of 27 Alumen samples collected from 8 production regions （Hunan， Anhui， Sichuan， Zhejiang， Jiangsu， Shandong， Shanxi， Henan） were subjected to preliminary identification based on visual characteristics. XRD PDF card comparison was used to differentiate Alumen from Ammonium alum. XRD characteristic profiles of Alumen were then established， and common peaks were screened. Based on hierarchical clustering analysis （HCA） and the variable importance projection （VIP） values > 1 from orthogonal partial least squares discrimination analysis （OPLS-DA）， characteristic information for white Alumen identification was selected. FTIR characteristic profiles of white Alumen were established， and key wavenumbers for identification were screened using HCA and OPLS-DA with VIP values > 1. Moreover， the thermogravimetric differences between Alumen and Ammonium alum were analyzed by TG-DTA to identify characteristic thermal signatures.ResultsBased solely on the observation of characteristics， it was not possible to effectively differentiate between Alumen and Ammonium alum. However， using the XRD PDF standard card comparison， 15 batches of white Alumen and 12 batches of Ammonium alum were identified. In the XRD profiles， ten characteristic peaks were confirmed， corresponding to diffraction angles of 14.560°， 24.316°， 12.620°， 32.122°， 17.898°， 34.642°， 27.496°， 46.048°， 40.697° and 21.973°. In the FTIR profiles， four wave number ranges （399.193~403.050 cm^-1、1 186.010~1 471.420 cm^-1、1 801.190~2 620.790 cm^-1、3 612.020~3 997.710 cm^-1） and twelve characteristic wave numbers （1 428.994、1 430.922、1 432.851、1 434.779、1 436.708、1 438.636、1 440.565、1 442.493、1 444.422、1 446.350、1 448.279、1 450.207 cm^-1） were identified. In the TG-DTA profiles， there were characteristic decomposition peaks of ammonium ions and mass reduction features near 555.34°C for Ammonium alum. These characteristics can serve as important criteria for distinguishing the authenticity of Alumen.ConclusionXRD， FTIR， and TG-DTA can be used to rapidly detect Alumen and Ammonium alum. By combining the discriminant features selected through chemometrics， rapid and accurate identification of Alumen and its counterfeit Ammonium alum can be achieved. The research findings provide new approaches for the rapid identification of Alumen.

Alumen;Ammonium alum;X-ray diffraction（XRD）;Fourier-transform infrared spectroscopy（FTIR）;thermogravimetric-differential thermal analysis（TG-DTA）;authenticity identification;chemometrics