Fumaric Acid
(fue mar' ik as' id).

C4H4O4 116.07
2-Butenedioic acid, E-;    
Fumaric acid     [110-17-8].
Fumaric Acid contains NLT 99.5% and NMT 100.5% of C4H4O4, calculated on the anhydrous basis.
•  Procedure
Sample solution:  Dissolve 1 g of Fumaric Acid in 50 mL of methanol, and warm gently on a steam bath to effect solution. Cool, and add phenolphthalein TS.
Analysis:  Titrate the Sample solution with 0.5 N sodium hydroxide VS to the first appearance of a pink color that persists for not less than 30 s. Perform a blank titration (see Titrimetry 541). Each mL of 0.5 N sodium hydroxide is equivalent to 29.02 mg of C4H4O4.
Acceptance criteria:  99.5%–100.5% on the anhydrous basis
Inorganic Impurities 
•  Residue on Ignition 281: NMT 0.1%
•  Heavy Metals, Method II 231: NMT 10 ppm
Organic Impurities 
•  Procedure: Limit of Maleic Acid
Mobile phase:  0.005 N sulfuric acid
Standard solution:  1 µg/mL of USP Maleic Acid RS in Mobile phase
Sample solution:  1 mg/mL of Fumaric Acid in Mobile phase
System suitability solution:  10 µg/mL of USP Fumaric Acid RS and 5 µg/mL of USP Maleic Acid RS in Mobile phase
Chromatographic system 
Mode:  LC
Detector:  UV 210 nm
Column:  4.6-mm × 22-cm; packing L17
Flow rate:  0.3 mL/min
Injection size:  5 µL
System suitability 
Sample:  System suitability solution
[Note—The relative retention times for maleic acid and fumaric acid are about 0.5 and 1.0, respectively. ]
Suitability requirements 
Resolution:  NLT 2.5 of the maleic acid and fumaric acid peaks
Relative standard deviation:  NMT 2.0% of the maleic acid peak
Samples:  Standard solution and Sample solution
Calculate the percentage of maleic acid in the total weight of Fumaric Acid taken:
Result = (rU/rS) × (CS/CU) × 100
rU== peak response of maleic acid from the Sample solution
rS== peak response of maleic acid from the Standard solution
CS== concentration of USP Maleic Acid RS in the Standard solution (mg/mL)
CU== nominal concentration of the Sample solution (mg/mL)
Acceptance criteria:  NMT 0.1%
•  Packaging and Storage: Preserve in well-closed containers.
•  USP Reference Standards 11
USP Fumaric Acid RS Click to View Structure
USP Maleic Acid RS Click to View Structure
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Robert H. Lafaver, M.S.
Scientific Liaison
(EXC2010) Monographs - Excipients
Reference Standards RS Technical Services
USP35–NF30 Page 1805
Pharmacopeial Forum: Volume No. 35(3) Page 598