Lysine Acetate

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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1 DEFINITION

Lysine Acetate contains NLT 98.0% and NMT 102.0% of l-lysine acetate (C₆H₁₄N₂O₂ · C₂H₄O₂), calculated on the dried basis.

2 IDENTIFICATION

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K

3 ASSAY

Procedure

Sample: 100 mg of Lysine Acetate

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. Titrate with the Titrant. Perform the Blank

determination.

Calculate the percentage of lysine acetate (C₆H₁₄N₂O₂ · C₂H₄O₂) in the Sample taken:

Result = {[(V_S − V_B) × N × F]/W} × 100

V_S = Titrant volume consumed by the Sample (mL)

V_B = Titrant volume consumed by the Blank (mL)

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

F = equivalency factor, 103.1 mg/mEq

W = Sample weight (mg)

Acceptance criteria: 98.0%–102.0% on the dried basis

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.4%

Chloride and Sulfate, Chloride〈221〉

Standard solution: 0.50 mL of 0.020 N hydrochloric acid

Sample: 0.73 g of Lysine Acetate

Acceptance criteria: NMT 0.05%

Chloride and Sulfate, Sulfate〈221〉

Standard solution: 0.10 mL of 0.020 N sulfuric acid

Sample: 0.33 g of Lysine Acetate

Acceptance criteria: NMT 0.03%

Change to read:

Iron 〈241〉, Procedures, Procedure 1 (CN 1-Jun-2023) : NMT 30 ppm

Change to read:

Related Compounds

Standard solution: 0.05 mg/mL of USP l-Lysine Acetate RS in water

[Note—This solution has a concentration equivalent to 0.5% of that of the Sample solution.]

Sample solution: 10 mg/mL of Lysine Acetate in water

System suitability solution: 0.4 mg/mL each of USP l-Lysine Acetate RS and USP Arginine Hydrochloride RS

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: Isopropyl alcohol and ammonium hydroxide (7:3)

Spray reagent: 2 mg/mL (ERR 1-Jun-2023) of ninhydrin in a mixture of butyl alcohol and 2 N acetic acid (95:5)

System suitability

Suitability requirements: The chromatogram of the System suitability solution exhibits two clearly separated spots.

Analysis

Samples: Standard solution, System suitability solution, and Sample solution

Dry the plate between 100° and 105° until the ammonia completely disappears. Spray with Spray reagent, and heat between 100° and 105° for 15 min. Examine the plate under white light.

Acceptance criteria: Any secondary spot of the Sample solution is not larger or more intense than the principal spot of the Standard solution.

Individual impurities: NMT 0.5%

Total impurities: NMT 2.0%

5 SPECIFIC TESTS

Optical Rotation, Specific Rotation〈781S〉

Sample solution: 100 mg/mL in water

Acceptance criteria: +8.4° to +9.9°

Loss on Drying 〈731〉: Dry a sample at 80° for 3 h: it loses NMT 0.2% of its weight.

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers.

USP Reference Standards 〈11〉

USP Arginine Hydrochloride RS

USP l-Lysine Acetate RS