Fluorescence spectral-chromaticity mapping for non-destructive authentication of herbal medicines

Identification of the authenticity of herbal medicines is crucial to ensure their safety and efficacy, yet quantitative, accurate, and practical identification methods remain limited. This work introduces a fluorescence-based approach for distinguishing authentic and counterfeit herbal medicines by analyzing their spectral and chromaticity features under 365 nm UV excitation. A hyperspectral imaging camera was employed to collect the spectral data from three groups of herbal medicines, Ziziphi Spinosae Semen (ZSS), Aurantii Fructus (AF), Carthami Flos (CF) and their common counterfeits (a total of 326 pieces of spectral data in the three groups, 158, 80, 88 respectively). The critical difference between ZSS, AF, CF and their counterfeits was obtained by extracting the fluorescence spectrum features. The mapping relationships between the spectrum features of ZSS and the colorimetric features were established by using the Fast Formula Fitting (FFF) and Neural Network Fitting (NNF) methods. The correlation coefficients of the two fitting methods in three groups were 0.985, 0.995, 0.999 and 0.992, 0.998, 0.989 respectively. The spectral power distribution in the range of 400-780 nm (good for AF, CF and their counterfeits) and 470-780 nm (good for ZSS and its counterfeits) were identified as optimal for color-based discrimination, guiding future filter selection for portable devices. Both methods enabled pixel-level authentication with high precision, supported by a defined chromaticity visualization zone. This non-destructive, quantitative technique facilitates simple and accurate herbal medicine verification, paving the way for low-cost, portable authenticity detection systems.