Alpha Lipoic Acid C8H14O2S2206.33 Thioctic acid; 1,2-Dithiolane-3-pentanoic acid; 1,2-Dithiolane-3-valeric acid [1077-28-7]. DEFINITION Alpha Lipoic Acid contains NLT 99.0% and NMT 101.0% of C8H14O2S2, calculated on the dried basis. IDENTIFICATION Change to read: • A.USP35 The retention time of the peak for alpha lipoic acid of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.Add the following: • B. Infrared Absorption 197K USP35ASSAY Change to read: • Procedure Buffer solution:USP35 0.68 g/L of monobasic potassium phosphate USP35Mobile phase: Methanol, Buffer solution, and acetonitrile (58:46:9). Adjust with phosphoric acid solution (8.3 in 100) to a pH of 3.03.1. USP35Standard solution: 1.0 mg/mL of USP Alpha Lipoic Acid RS in Mobile phaseUSP35 Sample solution: 1.0 mg/mL of Alpha Lipoic Acid in Mobile phaseUSP35 Chromatographic system Mode: LC Detector: UV 215 nm Column: 4.6-mm × 250-mm; packing L1 Column temperature: 35 Flow rate: 1.2 mL/min Injection size: 20 µL System suitability Sample: Standard solution Suitability requirements Column efficiency: NLT 10,000USP35 theoretical plates Tailing factor: NMT 2.0 for the alpha lipoic acid peak Relative standard deviation: NMT 2.0% for alpha lipoic acid Analysis Samples: Standard solution and Sample solution Calculate the percentage of alpha lipoic acid (C8H14O2S2) in the portion of Alpha Lipoic Acid taken: Result = (rU/rS) × (CS/CU) × 100
Acceptance criteria: 99.0%101.0% on the dried basis IMPURITIES • Residue on Ignition 281: Less than 0.1% • Heavy Metals, Method II 231: NMT 10 ppm Change to read: • Chromatographic Purity, Procedure 1 Buffer solution, Mobile phase, Standard solution, USP35 Sample solution, and Chromatographic system: Proceed as directed in the Assay. Diluted standard solution: Dilute the Standard solution (1 in 1000) with Mobile phase. System suitability USP35Sample: Diluted standard solution Suitability requirements Signal-to-noise ratio: NLT 10 Relative standard deviation: NMT 10.0% Analysis Sample: Sample solution Calculate the percentage of each impurity in the portion of Alpha Lipoic Acid taken: Result = (rU/rT) × 100
Acceptance criteria Individual impurities: NMT 0.1% Total impurities: NMT 2.0% • Chromatographic Purity, Procedure 2 [NoteUse low-actinic glassware. ] Standard solution A: 40.0 mg/mL of USP Alpha Lipoic Acid RS in dimethylformamide Standard solution B: 20.0 mg/mL of USP Alpha Lipoic Acid RS in dimethylformamide, prepared from the dilution of Standard solution A Standard solution C: 10.0 mg/mL of USP Alpha Lipoic Acid RS in dimethylformamide, prepared from the dilution of Standard solution B Sample solution: 40.0 mg/mL of Alpha Lipoic Acid in dimethylformamide Chromatographic system Mode: TLC Adsorbent: 0.25-mm layer of chromatographic silica gel mixture Application volume: 5 µL Developing solvent system: n-Propyl alcohol, ethyl acetate, water, and 25% ammonia water (40:40:10:5). Allow the chamber to become saturated for at least 1 h. Iodine vaporsaturated chamber: Transfer 4 g of iodine crystals to a small watch glass, and place in a chromatographic chamber. Allow the chamber to become saturated for at least 2 h. Analysis Samples: Standard solution A, Standard solution B, Standard solution C, and Sample solution Proceed as directed in the chapter, except to develop until the solvent front has moved 10 cm. Remove the plate, and allow to air-dry until the ammonia disappears completely. Heat at 50 for 20 min, cool the plate, and place in the Iodine vaporsaturated chamber until the spots are visible. The RF value for the alpha lipoic acid spot is 0.250.30 and for the polymeric lipoic acid spot is 0. Acceptance criteria: No spot other than the alpha lipoic acid spot from the Sample solution is more intense than the spot at RF = 0 from Standard solution A. SPECIFIC TESTS • Melting Range or Temperature 741: 60.062.0 • Optical Rotation, Specific Rotation 781S Sample solution: 50 mg/mL of Alpha Lipoic Acid, in dehydrated alcohol Acceptance criteria: 1.0 to +1.0 • Loss on Drying 731: Dry a sample in vacuum at 40 for 3 h: it loses NMT 0.2% 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 1366 Pharmacopeial Forum: Volume No. 37(1)Chromatographic Column Chromatographic columns text is not derived from, and not part of, USP 35 or NF 30. |