Macro-fingerprint analysis-through-separation of licorice based on FT-IR and 2DCOS-IR

•A stepwise analysis-through-separation approach based on multi-stage IR spectra (FT-IR, the second derivative IR and 2DCOS-IR) method was developed for analysis of the separation process of licorice.•Group-peak matching technique and spectral correlation coefficients were employed for the analysis.•The chemical compositions of licorice were comprehensively displayed from entirety to single active components.•The findings were supported by UPLC and a verification experiment of aqueous separation process.

In this paper, a step-by-step analysis-through-separation method under the navigation of multi-step IR macro-fingerprint (FT-IR integrated with second derivative IR (SD-IR) and 2DCOS-IR) was developed for comprehensively characterizing the hierarchical chemical fingerprints of licorice from entirety to single active components. Subsequently, the chemical profile variation rules of three parts (flavonoids, saponins and saccharides) in the separation process were holistically revealed and the number of matching peaks and correlation coefficients with standards of pure compounds was increasing along the extracting directions. The findings were supported by UPLC results and a verification experiment of aqueous separation process. It has been demonstrated that the developed multi-step IR macro-fingerprint analysis-through-separation approach could be a rapid, effective and integrated method not only for objectively providing comprehensive chemical characterization of licorice and all its separated parts, but also for rapidly revealing the global enrichment trend of the active components in licorice separation process.

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