Powdered Licorice
Powdered Licorice is Licorice reduced to a fine or very fine powder. It contains NLT 2.5% 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:  2 g of Powdered Licorice in 10 mL of a mixture of alcohol and water (7:3). Heat by shaking on a water bath for 5 min, cool, and filter.
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 500 mg of Powdered Licorice to a suitable flask. Add 70 mL of Diluent, shake for 15 min, centrifuge, and decant the supernatant into a 100-mL volumetric flask. Mix the residue with 25 mL of Diluent, shake for 15 min, centrifuge, and add the supernatant to the volumetric flask. Dilute with Diluent to volume, and filter.
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 determined from glycyrrhizic acid
Tailing factor:  NMT 2.0 for the glycyrrhizic acid peak
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 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== final volume of the Sample solution (mL)
WU== weight of Powdered Licorice taken to prepare the Sample solution (mg)
Acceptance criteria:  NLT 2.5% on the dried basis
•  Heavy Metals, Method III 231: NMT 30 µg/g
•  Botanic characteristics
Macroscopic:  It is light yellow-brown and has a slight odor and sweet taste.
Microscopic:  Under a microscope, Powdered Licorice reveals parenchyma cells containing starch grains and solitary crystals of calcium oxalate, parenchyma cell fragments, cork tissue, yellow sclerenchymatous fiber bundles that are accompanied by crystal cell rows, and vessels with reticulate and scalariform pits.
•  Loss on Drying 731: Dry a sample at 105 for 6 h: it loses NMT 12.0% of its weight.
•  Packaging and Storage: Store in well-closed containers in a cool, dry place.
•  Labeling: The label states the Latin binomial and, following the official name, the part of the plant contained in the article.
•  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 1363