(dye val' proe ex soe' dee um).
Pentanoic acid, 2-propyl-, sodium salt (2:1);
Sodium hydrogen bis(2-propylvalerate) oligomer.
Divalproex Sodium contains NLT 98.0% and NMT 102.0% of available valproic acid (C8H16O2).
• B. Identification TestsGeneral, Sodium 191
Sample: 100 mg
Analysis: Ignite the Sample.
Acceptance criteria: Meets the requirements
Solution A: 3.5 g of monobasic sodium phosphate monohydrate in 900 mL of water. Adjust with phosphoric acid to a pH of 3.5. Dilute with water to 1 L.
Mobile phase: Acetonitrile and Solution A (1:1)
Impurity stock solution: 0.5 mg/mL of USP Valproic Acid Related Compound A RS in acetonitrile
Standard stock solution: 5.0 mg/mL of USP Valproic Acid RS in Mobile phase
System suitability solution: 0.5 mg/mL of valproic acid from the Standard stock solution, and 5 µg/mL of valproic acid related compound A from the Impurity stock solution, in Mobile phase
Standard solution: 0.5 mg/mL of USP Valproic Acid RS from the Standard stock solution in Mobile phase
Sample solution: 0.5 mg/mL of Divalproex Sodium in Mobile phase
Detector: UV 215 nm
Column: 4.6-mm × 15-cm; 5-µm packing L7
Flow rate: 1 mL/min
Injection size: 20 µL
Sample: System suitability solution
[NoteThe relative retention times for valproic acid related compound A and valproic acid are 0.69 and 1.0, respectively. ]
Resolution: NLT 5.0 between valproic acid related compound A and valproic acid
Tailing factor: NMT 1.5 for the valproic acid peak
Relative standard deviation: NMT 2.0%
Samples: Standard solution and Sample solution
Calculate the percentage of available valproic acid (C8H16O2) in the portion of Divalproex Sodium taken:
Result = (rU/rS) × (CS/CU) × (Mr1/Mr2) × (1/F) × 100
Acceptance criteria: 98.0%102.0%
• Heavy Metals, Method II 231: NMT 20 ppm
• Water Determination, Method I 921: NMT 1.0%
• Packaging and Storage: Preserve in tight containers. Store at room temperature.
• USP Reference Standards 11
USP Divalproex Sodium RS
Sodium hydrogen bis(2-propylvalerate), oligomer; pentanoic acid, 2-propyl-, sodium salt (2:1).
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USP35NF30 Page 2945Pharmacopeial Forum: Volume No. 36(5) Page 1178