Simultaneous Determination of Six Compounds in Licorice and Related Chinese Herbal Preparations

An LC method was established for simultaneous determination of liquiritin, isoliquiritin, liquiritigenin, isoliquiritigenin, glycyrrhizic acid and glycyrrhetinic acid in licorice and related Chinese herbal preparations. Specifically, the mobile phase was composed of formic acid (0.04%, v/v) and acetonitrile using gradient elution steps as follows: 0–4 min, 80:20; 20 min, 62:38; 25 min, 45:55; 38–50 min, 10:90, and peaks were detected at 254 and 368 nm. All calibration curves showed good linear regression (r2 > 0.9987). The method showed good precision and accuracy with intra-day and inter-day variations of 0.917–3.884 and 1.484–4.886%, respectively, and recoveries of 94.484–105.263%. The developed method has been successfully applied to the simultaneous determination of 6 compounds in 13 licorice samples from different locations and 4 Chinese herbal preparations. The 6 compound levels in the samples were in the range of 2.617 ± 0.040–23.294 ± 0.846, 0.257 ± 0.005–7.799 ± 0.168, 0–1.948 ± 0.026, 0.040 ± 0.002–0.765 ± 0.007, 5.396 ± 0.442–624.207 ± 1.441, 0.063 ± 0.006–0.644 ± 0.006 mg g−1, respectively.