The determination of glycyrrhizic acid in Glycyrrhiza uralensis Fisch. ex DC. (Zhi Gan Cao) root and the dried aqueous extract by LC–DAD

• Published in: Journal of pharmaceutical and biomedical analysis 2008-07, Vol.47 (3), p.494-500
• Main Authors: Hennell, J.R., Lee, S., Khoo, C.S., Gray, M.J., Bensoussan, A.
• Format: Article
• Language: English
• Subjects: Analysis; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Chromatography, Liquid - methods; DAD; Fundamental and applied biological sciences. Psychology; General pharmacology; Glycyrrhiza uralensis - chemistry; Glycyrrhiza uralensis Fisch. ex DC; Glycyrrhizic acid; Glycyrrhizic Acid - analysis; Glycyrrhizin; Medical sciences; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Plant Extracts - analysis; Plant Roots - chemistry; Spectrometry, Mass, Electrospray Ionization; Validation; Zhi Gan Cao
• ISSN: 0731-7085; 1873-264X
• DOI: 10.1016/j.jpba.2008.01.037

A rapid, sensitive and specific reversed phase high-performance liquid chromatographic (LC) method with photodiode array detection (DAD) has been developed for the determination of glycyrrhizic acid in both the raw herb and a commercially prepared dried aqueous extract of Glycyrrhiza uralensis Fisch. ex DC. root (Zhi Gan Cao, liquorice). It was determined that extracting the raw herb in aqueous methanol (50:50 v/v) by sonication for 2 × 30 min was the most efficient sample preparation. Baseline resolution of the glycyrrhizic acid peak was achieved on a Varian Polaris RP C18-A (250 mm × 4.6 mm, 5 μm packing) column using an isocratic mobile phase consisting of 0.5 v/v aqueous phosphoric acid and acetonitrile in the ratio 60:40 v/v. Chromatograms were monitored between 200 and 400 nm for peak purity assessments, with quantitation performed at 254 nm. Glycyrrhizic acid calibration curves in the concentration range of 14–558 μg/ml were prepared on the day of analysis. Curve fitting was by the least-squares method, with correlation coefficients of >0.9998 obtained each time. The average recovery at three spike levels (50, 100, 200%) was of 95.91 ± 1.05% and 98.36 ± 3.45% (±S.D., n = 7) for the spiked raw herb and dried aqueous extract respectively. The limit of detection and limit of quantitation was 0.52 and 1.72 mg/g respectively for the raw herb, and 0.75 and 2.51 mg/g respectively for the dried aqueous extract. Identity confirmation of the chromatographic peak was achieved by (−) electrospray ionisation tandem mass spectrometry. The concentration of glycyrrhizic acid in the root and dried aqueous extract was found to be 31.1 ± 0.2 and 40.4 ± 0.3 mg/g (±S.D., n = 7) respectively.