Combination of the advantages of chromatographic methods based on active components for the quality evaluation of licorice.

A rapid, improved and comprehensive method including high-performance thin-layer chromatography, fingerprint technology and single standard to determine multiple components was developed and validated for the quality evaluation of licorice. In this study, a newly developed high-performance thin-layer chromatography method was first used for authentication of licorice, which achieved simultaneous identification of multiple bands including five bands for known bioactive components by comparing their retention factor values and colors with the standards. For fingerprint analysis, 8 of 16 common peaks were identified. Simultaneously, similarity analysis which showed very similar patterns and hierarchical clustering analysis were performed to discriminate and classify the 27 batches of samples. Additionally, the single standard to determine multiple components method was first successfully achieved to quantify the eight important active markers in licorice including liquiritin apioside, liquiritin, isoliquiritin apioside, isoliquritin, neoisoliquiritin, liquiritigenin, isoliquiritigenin and glycyrrhizic acid. The easily available glycyrrhizic acid was selected as the reference substance to calculate relative response factors. Compared with the normal external standard method, this alternative method can be used to determine the multiple indices effectively and accurately. The validation result showed that the developed method was specific, accurate, precise, robust and reliable for the overall quality assessment of licorice.