The determination of glycyrrhizic acid in Glycyrrhiza uralensis Fisch. ex DC. (Zhi Gan Cao) root and the dried aqueous extract by LC-DAD.
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 x 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 x 4.6 mm, 5 microm packing) column using an isocratic mobile phase consisting of 0. 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 microg/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+/-0.3mg/g (+/-S.D., n=7) respectively.
Hennell
J R
JR
Herbal Analysis and Pharmacological Laboratories (HAPL), Centre for Complementary Medicine Research, University of Western Sydney, Penrith South DC, 1797 NSW, Australia. j.hennell@uws.edu.au
Lee
S
S
Khoo
C S
CS
Gray
M J
MJ
Bensoussan
A
A
D002853:Chromatography, Liquid / Q000379:methods*; D029882:Glycyrrhiza uralensis / Q000737:chemistry*; D019695:Glycyrrhizic Acid / Q000032:analysis*; D010936:Plant Extracts / Q000032:analysis*; D018517:Plant Roots / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
D010936:Plant Extracts; D019695:Glycyrrhizic Acid