Analysis method of crude drug: Make licorice into powder, take about 0.5g of powder, weigh it accurately, put it in a centrifugal tube with a capacity of 50ml, add 25ml of mobile phase, put it in a reflux condenser tube, heat it in a water bath at 85℃ for 65,438 05min, cool it, centrifuge it, and transfer the supernatant to a 50ml volumetric bottle. The residue was extracted twice with mobile phase, each time with 10 ml, shaken for 5 minutes, centrifugally separated, and the supernatant was combined into a volumetric flask. Finally, the mobile phase is added to the balance as a sample solution.

In addition, take about 0.06 g of monoammonium glycyrrhizinate reference substance, weigh it accurately, put it in a 50 ml volumetric flask, add mobile phase to dissolve it, and adjust it to scale. Accurately measure 25 ml of this solution, put it in a 50 ml volumetric flask, add the mobile phase and calibrate it as a control solution.

Accurately take 10 microliter of sample solution and control solution and inject them into high performance liquid chromatograph, analyze them according to the above chromatographic conditions, determine the peak area of glycyrrhizic acid in each solution, and calculate the content of glycyrrhizic acid in the sample. The conversion coefficient of monoammonium glycyrrhizinate into glycyrrhizic acid is 0.9797. Glycyrrhiza uralensis samples from three different producing areas were analyzed and the content of glycyrrhizic acid was determined, as shown in Table 2:

Table 2 Sample Analysis Results