(lik' o rish).
Licorice consists of the roots, rhizomes, and stolons of Glycyrrhiza glabra L. or Glycyrrhiza uralensis Fish. ex DC. (Fam. Fabaceaeae). 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 pulverized 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 Licorice, reduced to a powder, 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 Licorice taken:
Result = (rU/rS) × CS × (V/W) × 100
rU== peak area of glycyrrhizic acid from the Sample solution
rS== peak area of 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)
W== weight of 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:  The terrestrial stem is nearly cylindrical, 0.5–3.0 cm in diameter, and over 1 m in length; it is externally dark brown to red-brown and longitudinally wrinkled. It often has lenticels, small buds, and scaly leaves. The transverse section reveals a rather clear border between the phloem and the xylem, and a radial structure that often has radiating splits.
Microscopic:  The transverse section reveals several yellow-brown cork layers, and a layer of phelloderm that is 1–3 cells thick. The cortex exhibits medullary rays, and obliterated sieve portions radiate alternately. The phloem exhibits groups of phloem fibers, which are surrounded by crystal cells, with thick but incompletely lignified walls. The vessels are accompanied by xylem fibers, which are surrounded by crystal cells, and by xylem parenchyma cells. The parenchyma cells contain starch grains, and often contain single crystals of calcium oxalate.
•  Loss on Drying 731: Dry a sample at 105 for 6 h: it loses NMT 12.0% of its weight.
•  Packaging and Storage: Preserve in well-closed containers. Store 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
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Topic/Question Contact Expert Committee
Monograph Maged H. Sharaf, Ph.D.
Principal Scientific Liaison
(DS2010) Monographs - Dietary Supplements
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USP35–NF30 Page 1362