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Cupric sulfate

Cupric sulfate suppliers and sourcing guide

Cupric sulfate is the copper (II) salt of sulfuric acid, made by reacting sulfuric acid with cupric oxide or copper metal. The usual form is the pentahydrate, deep blue crystals, granules or a light blue powder with about 25% copper; an anhydrous or monohydrate grade carries more. It dissolves readily in water and is used as a copper source in premixes and infant formula, and as a processing aid such as a fining agent in wine.

See suppliersWhat to ask for on the COA
Also known as
Copper sulfate · Copper (II) sulfate pentahydrate · Blue vitriol · Copper sulphate
Facts checked
November 2026

Forms and grades of cupric sulfate

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

  • Pentahydrate

    Blue crystals or powder, the standard food and USP grade.

  • Monohydrate or anhydrous

    Dried grades with more copper per gram and a lower moisture specification.

  • Triturations and premixes

    Cupric sulfate diluted on a carrier or blended with other trace minerals for even dosing.

What to check on the COA

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

Assay
Cupric sulfate content by iodometric titration, against the USP or Food Chemicals Codex specification for the hydrate ordered.
Iron and other metals
Limits on iron, lead, arsenic and cadmium by ICP-MS or ICP-OES.
Insoluble matter
Residue left after dissolving in water.
Water content
Loss on drying or ignition to confirm the hydrate form.

Storage, lots and expiry

Storage and shelf life

Store cupric sulfate in tightly closed containers in a cool, dry place; the pentahydrate slowly loses water in dry air and the dried grades take up moisture. Keep it away from metals it can corrode and from reducing agents. Shelf life is set by the supplier's specification, with assay and water content the usual retest checks.

Lots and expiry dates

Record the hydrate form and copper assay for each lot, because the copper per gram differs sharply between pentahydrate and dried grades. Keep food, USP and technical grades on separate item codes and never substitute agricultural material.

Regulatory status

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

  • 21 CFR 184.1261 affirms copper sulfate as GRAS for use in food as a nutrient supplement and processing aid at levels not exceeding current good manufacturing practice, and notes it is usually used as the pentahydrate.

    Source: ecfr.gov (opens in a new tab)

  • Health Canada's List of Food Additives with Other Accepted Uses permits copper sulphate as a fining agent in wine and fruit wine, with copper in the finished wine not to exceed 1 ppm.

    Source: canada.ca (opens in a new tab)

  • Health Canada's Multi-Vitamin/Mineral Supplements monograph for natural health products lists copper (II) sulfate and its monohydrate and pentahydrate among the source ingredients for copper (Table 2).

    Source: webprod.hc-sc.gc.ca (opens in a new tab)

  • 21 CFR 101.9(c)(8)(iv) sets the Reference Daily Intake for copper at 0.9 mg for adults and children 4 years and older.

    Source: ecfr.gov (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.

Cupric sulfate suppliers

Manufacturers and distributors whose own websites say they sell it.

We are checking cupric 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.

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Frequently asked questions

What forms of cupric sulfate can brands buy?

Common forms include pentahydrate, monohydrate or anhydrous and triturations and premixes. Ask each supplier for the specification sheet of the exact grade they quote.

What should the COA for cupric sulfate include?

Expect assay, iron and other metals, insoluble matter and water content, each with its method, specification and result for that lot.

How should cupric sulfate be stored?

Store cupric sulfate in tightly closed containers in a cool, dry place; the pentahydrate slowly loses water in dry air and the dried grades take up moisture. Keep it away from metals it can corrode and from reducing agents. Shelf life is set by the supplier's specification, with assay and water content the usual retest checks.

What is the regulatory status of cupric sulfate?

21 CFR 184.1261 affirms copper sulfate as GRAS for use in food as a nutrient supplement and processing aid at levels not exceeding current good manufacturing practice, and notes it is usually used as the pentahydrate. Health Canada's List of Food Additives with Other Accepted Uses permits copper sulphate as a fining agent in wine and fruit wine, with copper in the finished wine not to exceed 1 ppm. Health Canada's Multi-Vitamin/Mineral Supplements monograph for natural health products lists copper (II) sulfate and its monohydrate and pentahydrate among the source ingredients for copper (Table 2). 21 CFR 101.9(c)(8)(iv) sets the Reference Daily Intake for copper at 0.9 mg for adults and children 4 years and older.

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