Glutamine

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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C₅H₁₀N₂O₃ 146.14

L-Glutamine;

2-Aminoglutaramic acid CAS RN^®: 56-85-9; UNII: 0RH81L854J.

1 DEFINITION

Glutamine contains NLT 98.5% and NMT 101.5% of L-Glutamine (C₅H₁₀N₂O₃), calculated on the dried basis.

2 IDENTIFICATION

A. SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197K

3 ASSAY

PROCEDURE

Sample: 150 mg of Glutamine

Blank: Mix 3 mL of formic acid and 50 mL of glacial acetic acid.

Titrimetric system

(See Titrimetry (541).)

Mode: Direct titration

Titrant: 0.1 N perchloric acid VS

Endpoint detection: Potentiometric

Analysis: Dissolve the Sample in 3 mL of formic acid and 50 mL of glacial acetic acid, and titrate with the Titrant. Perform a Blank determination.

Calculate the percentage of glutamine (C₅H₁₀N₂O₃) in the Sample taken:

Result = {[(V_S - V_B) x N x F]/W} x 100

V_S = volume of Titrant consumed by the Sample (mL)

V_B = volume of Titrant consumed by the Blank (mL)

N = actual normality of the Titrant (mEq/mL)

F = equivalency factor, 146.1 mg/mEq

W = Sample weight (mg)

Acceptance criteria: 98.5%-101.5% on the dried basis

4 IMPURITIES

4.1 RESIDUE ON IGNITION (281)

NMT 0.3%

4.2 CHLORIDE AND SULFATE, Chloride (221)

Standard solution: 0.50 mL of 0.020 N hydrochloric acid

Sample: 0.7 g of Glutamine

Acceptance criteria: NMT 0.05%

4.3 CHLORIDE AND SULFATE, Sulfate (221)

Standard solution: 0.25 mL of 0.020 N sulfuric acid

Sample: 0.8 g of Glutamine

Acceptance criteria: NMT 0.03%

Change to read:

4.4 IRON (241), Procedures, Procedure 1 (CN 1-JUN-2023)

NMT 30 ppm

4.5 RELATED COMPOUNDS

Standard solution: 0.05 mg/mL of USP Glutamine RS in water

Sample solution: 10 mg/mL of Glutamine in water

Chromatographic system

(See Chromatography (621), Thin-Layer Chromatography.)

Mode: TLC

Adsorbent: 0.25-mm layer of chromatographic silica gel mixture

Application volume: 5 µL

Developing solvent system: Butyl alcohol, glacial acetic acid, and water (3:1:1)

Spray reagent: 2 mg/mL of ninhydrin in a mixture of butyl alcohol and 2 N acetic acid (95:5)

Analysis: Dry the plate at 80° for 30 min. Spray the plate with Spray reagent, heat at 80° for 10 min, and examine under white light.

Acceptance criteria: No secondary spot of the Sample solution is larger or more intense than the principal spot of the Standard solution (NMT 0.5%).

5 SPECIFIC TESTS

5.1 OPTICAL ROTATION, Specific Rotation(781S)

Sample solution: 40 mg/mL in water. Warm at 40° to dissolve.

Analysis: Proceed as directed in the chapter, except measure at 20°.

Acceptance criteria: +6.3° to +7.3°

5.2 LOSS ON DRYING (731)

Dry a sample at 105° for 3 h: it loses NMT 0.3% of its weight.

6 ADDITIONAL REQUIREMENTS

6.1 PACKAGING AND STORAGE

Preserve in well-closed containers, and store at controlled room temperature.

6.2 USP REFERENCE STANDARDS (11)

USP Glutamine RS