Powdered Licorice Extract
Powdered Licorice Extract is prepared from comminuted Licorice extracted with water or suitable solvents such as alcohol, water, or mixtures of these solvents. The ratio of the crude plant material to Powdered Extract is between 5:1 and 7:1. It contains NLT 6.0% of glycyrrhizic acid (C42H62O16), calculated on the dried basis.
•  A. Thin-Layer Chromatographic Identification Test
Standard solution:  5 mg/mL of USP Glycyrrhizic Acid RS in a mixture of alcohol and water (7:3)
Sample solution:  60 mg/mL of Powdered Licorice Extract, in a mixture of alcohol and water (1:1)
Chromatographic system 
Adsorbent:  0.25-mm layer of chromatographic silica gel mixture
Application volume:  2 µL
Developing solvent system:  Butyl alcohol, glacial acetic acid, and water (7:1:2)
Samples:  Standard solution and Sample solution
Develop the chromatogram in an unsaturated chamber to a length of 10 cm. Examine the plate under 254-nm light.
Acceptance criteria:  The chromatograms show a dark purple zone, among other spots, due to glycyrrhizic acid at an RF value of 0.4.
•  Content of Glycyrrhizic Acid
Diluent:  Alcohol and water (1:1)
Solution A:  Diluted acetic acid (1 in 15)
Mobile phase:  Acetonitrile and Solution A (2:3)
Standard solution:  0.25 mg/mL of USP Glycyrrhizic Acid RS in Diluent.
Sample solution:  Transfer 150 mg of Powdered Licorice Extract to a flask. Add 25 mL of Diluent, heat at 50 for 30 min, cool, centrifuge, and decant the supernatant into a 100-mL volumetric flask. Mix the residue with 20 mL of Diluent, repeat the above procedure, and dilute with Diluent to volume.
Chromatographic system 
Mode:  LC
Detector:  UV 254 nm
Column:  4.6-mm × 15-cm; packing L1
Flow rate:  0.6 mL/min
Injection size:  20 µL
System suitability 
Sample:  Standard solution
Suitability requirements 
Column efficiency:  NLT 5000 theoretical plates
Tailing factor:  NMT 2.0
Relative standard deviation:  NMT 2.0%
Samples:  Standard solution and Sample solution
Calculate the percentage of glycyrrhizic acid (C42H62O16) in the portion of Powdered Licorice Extract taken:
Result = (rU/rS) × CS × (V/W) × 100
rU == peak area for glycyrrhizic acid from the Sample solution
rS == peak area for glycyrrhizic acid from the Standard solution
CS == concentration of USP Glycyrrhizic Acid RS in the Standard solution (mg/mL)
V == volume of Sample solution, 100 mL
W== weight of Powdered Licorice Extract taken to prepare the Sample solution (mg)
Acceptance criteria:  NLT 6.0% on the dried basis
•  Heavy Metals, Method III 231: NMT 30 µg/g
•  Loss on Drying 731: Dry a sample at 105 for 6 h: it loses NMT 10.0% of its weight.
•  Packaging and Storage: Preserve in tight containers, protected from light.
•  Labeling: The label states the Latin binomial and, following the official name, the part of the plant from which the article was derived. The label also indicates the content of glycyrrhizic acid, the extracting solvent or solvent mixture used for preparation, and the ratio of the starting material to final product. The label bears a statement indicating that “Excessive amounts or long-term use of Licorice may cause high blood pressure or low potassium, which have been associated with irregular heartbeat and/or muscle weakness. Licorice may worsen the effects of congestive heart failure, cirrhosis, or kidney failure. Diuretic use may increase the risk. If you are pregnant or nursing a baby, seek the advice of a health professional before using this product.” It meets the requirements in Botanical Extracts 565, Labeling.
•  USP Reference Standards 11
USP Glycyrrhizic Acid RS Click to View Structure
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Maged H. Sharaf, Ph.D.
Principal Scientific Liaison
(DS2010) Monographs - Dietary Supplements
Reference Standards RS Technical Services
USP35–NF30 Page 1364
Pharmacopeial Forum: Volume No. 30(2) Page 574