Ferrous sulfate

Ferrous sulfate suppliers and sourcing guide

Ferrous sulfate is the iron (II) salt of sulfuric acid, made by dissolving iron in sulfuric acid and crystallizing the heptahydrate, which forms pale bluish-green crystals with about 20% iron. Heating the heptahydrate drives off water to give dried ferrous sulfate, a grayish-white powder that is mostly the monohydrate and carries about 30% or more iron. Brands buy the dried or encapsulated grades for tablets, premixes and flour or cereal fortification.

See suppliers What to ask for on the COA

Category: Vitamins and minerals
Also known as: Iron (II) sulfate · Ferrous sulfate heptahydrate · Dried ferrous sulfate · Ferrous sulphate
Facts checked: November 2026

Forms and grades of ferrous sulfate

Suppliers sell different products under the same name. Specify the one you need.

Heptahydrate
Crystals or granules with seven waters of hydration, used in liquids and where a soluble iron salt is needed.
Dried (monohydrate)
Powder with most of the water removed, giving more iron per gram and better stability in dry blends and tablets.
Encapsulated
Dried ferrous sulfate coated with fat or another barrier to limit reactions with other ingredients and off-flavors in fortified foods.
Fine powder grades
Milled grades with a stated particle size for flour and cereal premixes.

What to check on the COA

Compare each result with your own specification when the lot arrives.

Assay: Ferrous sulfate content by ceric or permanganate titration, against the Food Chemicals Codex or USP specification for the hydrate ordered.
Iron content: Iron as a percentage of the powder, which differs sharply between the heptahydrate and dried forms.
Ferric iron: A limit on oxidized iron, which rises when the material is exposed to air and moisture.
Loss on drying or water content: Confirms the hydrate form and checks for excess moisture.
Lead and mercury: Heavy metals by ICP-MS against the compendial or supplier limits.
Particle size: Sieve analysis for fortification grades, where fine, even particles mix better into flour.

Storage, lots and expiry

Storage and shelf life

Store ferrous sulfate in tightly closed containers in a cool, dry place; the heptahydrate loses water in dry air and oxidizes to brownish ferric salts in moist air. Keep it away from oxidizing materials and reseal opened packs. Shelf life is set by the supplier's specification, and older lots are retested for assay and ferric iron.

Lots and expiry dates

Record which hydrate each lot is and its actual iron content, because swapping heptahydrate for dried material changes the iron dose by about half. Check color on receipt, since yellow-brown crystals point to oxidation.

Regulatory status

Facts from regulators and standards bodies, each linked to its source.

21 CFR 184.1315 affirms ferrous sulfate (heptahydrate and dried) as GRAS for use in food as a nutrient supplement and processing aid, with no limitation other than current good manufacturing practice.
Source: ecfr.gov (opens in a new tab)
7 CFR 205.605(b) allows ferrous sulfate in processed products labeled organic for iron enrichment or fortification when required by regulation or recommended by an independent organization.
Source: ecfr.gov (opens in a new tab)
21 CFR 101.17(e) requires dietary supplements in solid oral dosage form that contain iron or iron salts as an iron source to carry a boxed accidental-overdose warning statement.
Source: ecfr.gov (opens in a new tab)
Health Canada's Multi-Vitamin/Mineral Supplements monograph for natural health products lists dried iron (II) sulfate and iron (II) sulfate heptahydrate among the source ingredients for iron (Table 2).
Source: webprod.hc-sc.gc.ca (opens in a new tab)

This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.

Ferrous sulfate suppliers

Manufacturers and distributors whose own websites say they sell it.

We are checking ferrous sulfate suppliers now

Every listing is checked against the supplier’s own website before it goes live, so this list fills in over the coming weeks. The specs and COA checklist above are ready today.

Sell ferrous sulfate? Request a listing

Frequently asked questions

What forms of ferrous sulfate can brands buy?

Common forms include heptahydrate, dried (monohydrate), encapsulated and fine powder grades. Ask each supplier for the specification sheet of the exact grade they quote.

What should the COA for ferrous sulfate include?

Expect assay, iron content, ferric iron, loss on drying or water content, lead and mercury and particle size, each with its method, specification and result for that lot.

How should ferrous sulfate be stored?

What is the regulatory status of ferrous sulfate?

21 CFR 184.1315 affirms ferrous sulfate (heptahydrate and dried) as GRAS for use in food as a nutrient supplement and processing aid, with no limitation other than current good manufacturing practice. 7 CFR 205.605(b) allows ferrous sulfate in processed products labeled organic for iron enrichment or fortification when required by regulation or recommended by an independent organization. 21 CFR 101.17(e) requires dietary supplements in solid oral dosage form that contain iron or iron salts as an iron source to carry a boxed accidental-overdose warning statement. Health Canada's Multi-Vitamin/Mineral Supplements monograph for natural health products lists dried iron (II) sulfate and iron (II) sulfate heptahydrate among the source ingredients for iron (Table 2).

More vitamins and minerals

All 75 vitamins and minerals

Sell ingredients to brands?

Request a free listing for the ingredients you make or distribute. No paid placement.

Request a listing