Characterization of the Simulated Procedure for Preparation of Dried Radix Rehmanniae Using IR-CWT-ICA Approach

For characterization of the procedure for preparation of dried radix rehmanniae, the processing procedure was simulated in laboratory by varying the dried temperature from 40degC to 100degC during more than 50 h. The attenuated total reflectance (ATR) FTIR of the sample at different time periods were measured, then the measured IR spectra were pretreated by continuous wavelet transform (CWT), and the CWT coefficients, which can present the IR features of the sample, were processed by kernel independent component analysis (KICA). The estimated independent components (ICs) and their variation of relative concentrations that were calculated by nonnegative least square (NNLS) were used to characterize the preparation procedure. The results show that the components nearly keep invariant during the first 22 h at 40degC; the most obvious change trend of the components is in the range of 22~34 h at 50degC; after 34 h and above 50degC, the relative concentration of the components varies slightly with a decreased trend. The IR-CWT-KICA method can be used for characterization of the procedure for preparing dried radix rehmanniae.