(as kore' bik as' id).
Ascorbic Acid contains NLT 99.0% and NMT 100.5% of C6H8O6.
• B. A 20-mg/mL solution reduces alkaline cupric tartrate TS slowly at room temperature but more readily upon heating.
Sample: 400 mg of Ascorbic Acid
(See Titrimetry 541.)
Mode: Direct titration
Titrant: 0.1 N iodine VS
Endpoint detection: Visual
Blank: 100 mL of water and 25 mL of 2 N sulfuric acid. Add 3 mL of starch TS.
Analysis: Dissolve the Sample in a mixture of 100 mL of water and 25 mL of 2 N sulfuric acid. Add 3 mL of starch TS, and titrate immediately with Titrant until a persistent violet-blue color is obtained.
Calculate the percentage of ascorbic acid (C6H8O6) in the portion of Ascorbic Acid taken:
Result = [(V B) × N × F × 100]/W
Acceptance criteria: 99.0%100.5%
• Residue on Ignition 281: NMT 0.1%
• Heavy Metals 231
Sample solution: 1 g in 25 mL of water
Acceptance criteria: NMT 20 ppm
• Optical Rotation, Specific Rotation 781S
Sample solution: 100 mg/mL in carbon dioxide-free water. Perform the test immediately after preparation of the Sample solution.
Acceptance criteria: +20.5 to +21.5
• Packaging and Storage: Preserve in tight, light-resistant containers.
• USP Reference Standards 11
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USP35NF30 Page 2242