Malic Acid
» Malic Acid contains not less than 99.0 percent and not more than 100.5 percent of C4H6O5.
Packaging and storage
Preserve in well-closed containers.
Identification, Infrared Absorption
![]() ![]()
Residue on ignition
![]() ![]()
Water-insoluble substances
Dissolve 25 g in 100 mL of water, filter the solution through a tared filtering crucible, wash the filter with hot water, and dry at 100
![]()
Heavy metals, Method II
![]() ![]()
Fumaric and maleic acids
Mobile phase
Prepare a suitable filtered and degassed 0.01 N sulfuric acid in water solution.
Standard preparation
Using Mobile phase as a solvent, prepare a solution containing accurately known concentrations of about 0.005 mg of USP Fumaric Acid RS per mL and about 0.002 mg of USP Maleic Acid RS per mL.
Test preparation
Transfer about 100 mg, accurately weighed, of Malic Acid to a 100-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.
Resolution solution
Using Mobile phase as a solvent, prepare a solution containing about 1 mg of Malic Acid per mL, about 10 µg of USP Fumaric Acid RS per mL, and about 4 µg of USP Maleic Acid RS per mL.
Chromatographic system
(see Chromatography
![]() ![]() ![]()
Procedure
Separately inject equal volumes (about 20 µL) of the Standard preparation and the Test preparation into the chromatograph, record the chromatograms, and measure the peak responses. The relative retention times are about 0.6 for maleic acid, 1.0 for malic acid, and about 1.5 for fumaric acid. Calculate the quantities, in mg, of maleic acid and of fumaric acid in the portion of Malic Acid taken by the formula:
100C(rU / rS)
in which C is the concentration, in mg per mL, of the corresponding reference standard in the Standard preparation; and rU and rS are the responses of the corresponding peaks from the Test preparation and the Standard preparation, respectively. Not more than 1.0% of fumaric acid and not more than 0.05% of maleic acid are found.
Assay
Transfer about 2 g of Malic Acid, accurately weighed, to a conical flask, dissolve in 40 mL of recently boiled and cooled water, add phenolphthalein TS, and titrate with 1 N sodium hydroxide VS to the first appearance of a faint pink color that persists for not less than 30 seconds. Each mL of 1 N sodium hydroxide is equivalent to 67.04 mg of C4H6O5.
Auxiliary Information
Please check for your question in the FAQs before contacting USP.
Chromatographic Column
USP32NF27 Page 1274
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.
|