Methionine (me thye' oh neen). DEFINITION Methionine contains NLT 98.5% and NMT 101.5% of l-methionine (C5H11NO2S), calculated on the dried basis. IDENTIFICATION ASSAY • Procedure Sample: 140 mg of Methionine 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. Calculate the percentage of methionine (C5H11NO2S) in the Sample taken: Result = {[(VS VB) × N × F]/W} × 100
Acceptance criteria: 98.5%101.5% on the dried basis 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 Methionine 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 Methionine Acceptance criteria: NMT 0.03 % • Iron 241: NMT 30 ppm • Heavy Metals, Method I 231: NMT 15 ppm • Related Compounds System suitability solution: 0.4 mg/mL each of USP l-Methionine RS and USP l-Serine RS in 0.3 N hydrochloric acid Standard solution: 0.05 mg/mL of USP l-Methionine RS in 0.3 N hydrochloric acid. [NoteThis solution has a concentration equivalent to 0.5% of that of the Sample solution. ] Sample solution: 10 mg/mL of Methionine in 0.3 N hydrochloric acid Chromatographic system 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) System suitability Suitability requirements: The chromatogram of the System suitability solution exhibits two clearly separated spots. Analysis Samples: System suitability solution, Standard solution, and Sample solution After air-drying the plate, 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% SPECIFIC TESTS • Optical Rotation, Specific Rotation 781S Sample solution: 20 mg/mL in 6 N hydrochloric acid Acceptance criteria: +22.4 to +24.7 • Loss on Drying 731: Dry a sample at 105 for 3 h: it loses NMT 0.3% of its weight. ADDITIONAL REQUIREMENTS • Packaging and Storage: Preserve in well-closed containers. Auxiliary Information Please check for your question in the FAQs before contacting USP.
USP35NF30 Page 3851 Chromatographic Column Chromatographic columns text is not derived from, and not part of, USP 35 or NF 30. |