Article Title

Development of an assay method for natural products containing cosmetics (II)-licorice


This study established a quantification method for cosmetics containing licorice. During pretreatment, methanol was used as a solvent for extraction of lotion products and a salting-out method with a photodiode array detector for emulsions and creams. A gradient high performance liquid chromatographic method was established to determine liquiritin, glycyrrhizin and glycyrrhetinic acid in licorice-containing cosmetics. Samples were analyzed by gradient elution with a mobile phase containing acetonitrile and 1% phosphoric acid at a flow rate of 1.0 mL/min. Calibration curves of the three compounds were constructed in the range of 5.0-50.0 μg/mL in glycerin solution and 2.5-100.0 μg/mL in emulsion and cream. The correlation coefficients were all above 0.994. The average recoveries of these three compounds were 88.8-107.4%, 91.7-104.1% and 95.6-105.5% in glycerin solution, emulsion, and cream, respectively. The analytical method was further validated and employed in the assay of the commercial products. The results showed that glycyrrhizin could be detected in licorice extracts. With regard to the quantification of marker components in commercial products, glycyrrhizin (16.8 to 113.4 μg/mL) was detected in 3 out of 7 licorice-containing commercial products. Glycyrrhizin was the most abundant component in licorice, while other marker compounds were not detectable, probably due to low contents or extensive dilution. The method developed in this study can be applied to commercial cosmetics containing licorice for the assurance of product quality.

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