DETERMINATION OF GLYCYRRHIZIC ACID IN ROOTS OF LICORICE BY HPLC METHOD WITH SUBCRITICAL DYNAMIC EXTRACTION
Glycyrrhizic acid belongs to triterpene saponins and is the target component in obtaining extracts from the licorice root (Glycyrrhiza glabra). In the current paper, a technique has been developed for the determination of glycyrrhizic acid (GA) in licorice roots using the method of high-performance liquid chromatography (HPLC) with the preliminary extraction under subcritical conditions. To optimize the conditions for the sample preparation, an assessment was made of the efficiency of HA extraction with water and ammonia solutions at temperatures of 120, 150 and 170 °C and 5 MPa pressure under the dynamic conditions in comparison with the extraction on a water bath with water, solutions of ammonia, acetone, and 3% solution of nitric acid in acetone. It was shown that the maximum extraction of GA under all the extraction modes studied was carried out by the extraction with water at t = 150 ºC and a flow rate of 1.7 cm3/min, comparable results are obtained by extraction with a 3% solution of ammonia under the same conditions. For the quantitative analysis, it was proposed to use the HPLC method with gradient elution. It was shown that the application of the developed technique allows for more accurate identification and quantitative determination of GA in licorice roots in comparison with the traditionally used gravimetric method.