Ferrous Fumarate Tablets
DEFINITION
Ferrous Fumarate Tablets contain NLT 95.0% and NMT 110.0% of the labeled amount of ferrous fumarate (C4H2FeO4).
IDENTIFICATION
•  A. Identification Tests—General, Iron 191
Sample solution:  To a portion of powdered Tablets, equivalent to 1 g of ferrous fumarate, add 25 mL of dilute hydrochloric acid (1 in 2), mix, and add 25 mL of water. Boil the solution for a few min, cool, and filter.
Acceptance criteria:  The filtrate meets the requirements.
ASSAY
•  Procedure
Sample:  A portion of the powder from NLT 20 finely powdered Tablets equivalent to 500 mg of ferrous fumarate
Blank:  Proceed as in the Analysis without the Sample.
Titrimetric system 
Mode:  Indirect titration
Titrant:  0.1 N sodium thiosulfate VS
Indicator:  Starch TS
Endpoint detection:  Visual
Analysis:  Transfer the Sample to a 250-mL beaker. Add 25 mL of water, 25 mL of nitric acid, and 7.5 mL of perchloric acid. Cover with a ribbed watch glass, and heat to the production of strong fumes. Cool, rinse the watch glass and the sides of the beaker with water, and evaporate in a hood to near-dryness. Wash down the watch glass and the sides of the beaker with 2 mL of hydrochloric acid and then with a small volume of water. Warm slightly, if necessary, to dissolve the residue. Transfer to a glass-stoppered, 250-mL conical flask. Repeat the washing with 2 mL of hydrochloric acid, and complete the transfer to the flask, using NMT 20–25 mL of water for the transfer. Add 4 g of potassium iodide to the flask, insert the stopper, and allow to stand in the dark for 5 min. Add 75 mL of water and titrate with Titrant, adding 3 mL of starch TS as the endpoint is approached. Perform a blank determination.
Calculate the percentage of the labeled amount of ferrous fumarate (C4H2FeO4) in the portion of Tablets taken:
Result = {[(VS VB) × N × F]/W} × 100
VS== Titrant volume consumed by the Sample (mL)
VB== Titrant volume consumed by the Blank (mL)
N== actual normality of the Titrant (mEq/mL)
F== equivalency factor, 169.9 mg/mEq
W== nominal weight of ferrous fumarate in the Sample taken (mg)
Acceptance criteria:  95.0%–110.0%
PERFORMANCE TESTS
•  Dissolution 711
Medium:  0.1 N hydrochloric acid in 0.5% sodium lauryl sulfate; 900 mL
Apparatus 2:  75 rpm
Time:  45 min
Standard solution:  Solution having a known concentration of iron in the Medium
Sample solution:  Filtered portion of the solution under test, suitably diluted with the Medium if necessary
Instrumental conditions 
Mode:  Atomic absorption spectrophotometry
Analytical wavelength:  248.3 nm
Lamp:  Iron hollow-cathode
Flame:  Air–acetylene
Analysis 
Samples:  Standard solution and Sample solution
Determine the concentration of iron (Fe) in the Sample solution in comparison with a Standard solution.
Calculate the percentage of the labeled amount of ferrous fumarate (C4H2FeO4) dissolved:
Result = (Mr/Ar) × (C × D × V/L) × 100
Mr== molecular weight of ferrous fumarate, 169.9
Ar== atomic weight of iron, 55.85
C== measured concentration of iron in the Sample solution (mg/mL)
D== dilution factor for the Sample solution
V== volume of Medium, 900 mL
L== label amount of ferrous fumarate (mg/Tablet)
Tolerances:  NLT 75% (Q) of the labeled amount of ferrous fumarate is dissolved.
•  Uniformity of Dosage Units 905: Meet the requirements
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in tight containers.
•  Labeling: Label the Tablets in terms of ferrous fumarate (C4H2FeO4) and in terms of elemental iron.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Natalia Davydova
Scientific Liaison
1-301-816-8328
(DS2010) Monographs - Dietary Supplements
711 Margareth R.C. Marques, Ph.D.
Senior Scientific Liaison
1-301-816-8106
(GCDF2010) General Chapters - Dosage Forms
USP35–NF30 Page 3173