Spectral and chromatographic overall analysis: An insight into chemical equivalence assessment of traditional Chinese medicine

Abstract Several issues are associated with the use of high-performance liquid chromatography-diode-array detector (HPLC-DAD) analysis in the evaluation of the chemical equivalence of traditional Chinese medicine (TCM), such as the choice of representative wavelengths, quick and efficient integration, correct matching of different components, and full use of spectral information. These problems can be addressed by handling raw three-dimensional (3D) data in a different manner, which led to the development of the spectral and chromatographic overall analysis (SCOA) method. In SCOA, the Whittaker smoother is used to eliminate the baseline drift caused by solvents, and the projection profiling is extracted from 3D data as the most informative chromatogram. Peak matching takes advantage of spectral similarity to exclude spectrally dissimilar components in the matching group. Subsequently, the exponential-Gaussian hybrid function (EGH) is used to fit and integrate the projection profiling, thus avoiding the cumbersome and time-consuming integration process. Two data sets were used to validate and demonstrate the SCOA. The results show that the SCOA is more comprehensive and reliable than HPLC-DAD analysis in the chemical equivalence assessment of TCM.