Ferrous Sulfate Syrup
Ferrous Sulfate Syrup contains, in each 100 mL, NLT 3.75 g and NMT 4.25 g of ferrous sulfate heptahydrate (FeSO4·7H2O), equivalent to NLT 0.75 g and NMT 0.85 g of elemental iron.
Ferrous Sulfate Syrup is prepared as follows.
Ferrous Sulfate 40 g
Citric Acid, hydrous 2.1 g
Peppermint Spirit 2 mL
Sucrose 825 g
Purified Water, a sufficient quantity
to make
1000 mL
Dissolve the Ferrous Sulfate, Citric Acid, Peppermint Spirit, and 200 g of Sucrose in 450 mL of Purified Water, and filter the solution until clear. Dissolve the remainder of the Sucrose in the clear filtrate, and add Purified Water to make 1000 mL. Mix, and filter if necessary, through a pledget of cotton.
•  A. Identification Tests—General, Iron, Ferrous Salts 191 and Sulfate 191
Sample solution:  Dilute 1 mL of Syrup with water to 100 mL.
Acceptance criteria:  Meets the requirements
•  Procedure
Sample:  25 mL of Syrup
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:  Add 15 mL of 2 N sulfuric acid and 100 mL of water to the Sample, and shake well. Add 3 drops of orthophenanthroline TS, and titrate with Titrant until the color changes. Perform a blank determination.
Calculate the amount of ferrous sulfate heptahydrate (FeSO4·7H2O) in g per each 100 mL of Syrup:
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, 0.278 g/mEq
W== volume of Ferrous Sulfate Syrup for the Sample taken (mL)
Acceptance criteria:  3.75–4.25 g in each 100 mL
•  Packaging and Storage: Preserve in tight containers.
•  Labeling: Label the Syrup in terms of the content of ferrous sulfate (FeSO4·7H2O) and in terms of the content 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
(DS2010) Monographs - Dietary Supplements
USP35–NF30 Page 3181