(mal' ik as' id).
Malic Acid contains NLT 99.0% and NMT 100.5% of C4H6O5.
• A. Infrared Absorption 197K: On undried sample
Sample: 2 g
(See Titrimetry 541.)
Mode: Direct titration
Titrant: 1 N sodium hydroxide VS
Endpoint detection: Visual
Analysis: Dissolve the Sample in 40 mL of recently boiled and cooled water. Add phenolphthalein TS, and titrate to the first appearance of a faint pink color that persists for NLT 30 s. Perform a blank determination.
Calculate the percentage of malic acid (C4H6O5) in the Sample taken:
Result = [(V B) × N × F × 100]/W
Acceptance criteria: 99.0%100.5%
• Residue on Ignition 281: NMT 0.1%
• Heavy Metals, Method II 231: NMT 20 ppm
• Fumaric and Maleic Acids
Mobile phase: 0.01 N sulfuric acid
System suitability solution: 1 mg/mL of Malic Acid, 10 µg/mL of USP Fumaric Acid RS, and 4 µg/mL of USP Maleic Acid RS in Mobile phase
Standard solution: 5.0 µg/mL of USP Fumaric Acid RS and 2.0 µg/mL of USP Maleic Acid RS in Mobile phase
Sample solution: 1.0 mg/mL of Malic Acid in Mobile phase
Detector: UV 210 nm
Column: 6.5-mm × 30-cm; packing L17
Column temperature: 37 ± 1
Flow rate: 0.6 mL/min
Injection size: 20 µL
Sample: System suitability solution
[NoteThe relative retention times for maleic acid, malic acid, and fumaric acid are 0.6, 1.0, and 1.5, respectively. ]
Resolution: NLT 2.5 for the maleic acid and malic acid peaks; NLT 7.0 for the malic acid and fumaric acid peaks
Relative standard deviation: NMT 2.0% for the maleic acid peak
Samples: Standard solution and Sample solution
Calculate the percentage of maleic acid and of fumaric acid in the portion of Malic Acid taken:
Result = (rU/rS) × (CS/CU) × 100
Fumaric acid: NMT 1.0%
Maleic acid: NMT 0.05%
• Water-Insoluble Substances
Sample: 25 g
Analysis: Dissolve the Sample in 100 mL of water, filter the solution through a tared filtering crucible, wash the filter with hot water, and dry at 100 to constant weight.
Acceptance criteria: The increase in weight is NMT 25 mg (0.1%).
• Packaging and Storage: Preserve in well-closed containers.
• USP Reference Standards 11
Auxiliary Information Please check for your question in the FAQs before contacting USP.
USP35NF30 Page 1851