Ferrous Sulfate Tablets
DEFINITION
Ferrous Sulfate Tablets contain NLT 95.0% and NMT 110.0% of the labeled amount of ferrous sulfate heptahydrate (FeSO4·7H2O). [Note—An equivalent amount of Dried Ferrous Sulfate may be used in place of FeSO4·7H2O in preparing Ferrous Sulfate Tablets. ]
IDENTIFICATION
Sample solution:  Equivalent to 10 mg/mL of ferrous sulfate heptahydrate from powdered Tablets in water acidified with hydrochloric acid
Acceptance criteria:  Meets the requirements
ASSAY
•  Procedure
Sample:  Equivalent to 500 mg of ferrous sulfate heptahydrate from finely powdered Tablets (NLT 20)
Blank:  Proceed as in the Analysis without the Sample.
Titrimetric system
Mode:  Direct titration
Titrant:  0.1 N ceric sulfate VS
Indicator:  Orthophenanthroline TS
Endpoint detection:  Visual
Analysis:  In a beaker, dissolve the Sample in a mixture of 20 mL of 2 N sulfuric acid and 80 mL of freshly boiled and cooled water. Filter the solution rapidly as soon as all soluble ingredients in the Tablets are dissolved, and wash the container and the filter with small portions of a mixture of 20 mL of 2 N sulfuric acid and 80 mL of freshly boiled and cooled water.
Add orthophenanthroline TS, and immediately titrate the filtrate in the suction flask with Titrant until the color changes. Perform a blank determination.
Calculate the percentage of the labeled amount of ferrous sulfate heptahydrate (FeSO4·7H2O) in the Sample 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, 278.0 mg/mEq W = = nominal weight of ferrous sulfate heptahydrate in the Sample taken (mg)
Acceptance criteria:  95.0%–110.0%
PERFORMANCE TESTS
Medium:  0.1 N hydrochloric acid; 900 mL
Apparatus 2:  50 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
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 sulfate heptahydrate (FeSO4·7H2O) dissolved:
Result = (Mr/Ar) × (C × D × V/L) × 100
 Mr = = molecular weight of ferrous sulfate heptahydrate, 278.02 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 claim (mg/Tablet)
Tolerances:  NLT 75% (Q) of the labeled amount of ferrous sulfate heptahydrate (FeSO4·7H2O) is dissolved.
Meet the requirements