Sodium metabisulphite is a widely used industrial and food-grade chemical with applications across food processing, pharmaceuticals, water treatment, mining, and manufacturing. For importers, distributors, and industrial buyers, understanding the sodium metabisulphite CAS No, quality specifications, and sourcing requirements is essential for compliance and safe usage.

This guide explains what sodium metabisulphite is, its CAS number, key applications, regulatory considerations, and how to source it reliably for African and global markets.

What Is Sodium Metabisulphite?

Sodium metabisulphite is an inorganic compound commonly supplied as a white or slightly yellow crystalline powder with a strong sulphur dioxide smell. It is primarily used as:

• A preservative and antioxidant

• A reducing agent

• A disinfectant and bleaching aid

It is highly soluble in water and reacts readily with acids to release sulphur dioxide (SO₂), which gives it its antimicrobial properties.

Sodium Metabisulphite CAS No Explained

The CAS number for sodium metabisulphite is 7681-57-4.

A CAS (Chemical Abstracts Service) number is a globally recognised identifier that ensures chemicals are accurately classified and regulated across international markets. Using the correct CAS number is critical for:

• Import and export documentation

• Safety Data Sheets (SDS)

• Customs clearance

• Regulatory compliance

• Quality verification

For businesses sourcing chemicals at scale, verifying the CAS number helps avoid mislabelling, shipment delays, or regulatory penalties.

Common Uses of Sodium Metabisulphite

Food and Beverage Industry

Food-grade sodium metabisulphite is widely used as a preservative (E223) to prevent oxidation and microbial growth in:

• Dried fruits

• Fruit juices and concentrates

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• Wine and beer

• Processed potatoes and baked goods

Proper dosage and food-grade certification are essential to meet food safety regulations.

Pharmaceutical and Medical Applications

In pharmaceuticals, sodium metabisulphite acts as an antioxidant to stabilise active ingredients in injectable drugs and oral formulations. Pharmaceutical-grade purity is required, along with full documentation.

Water Treatment

Sodium metabisulphite is commonly used to remove excess chlorine and chloramine in:

• Municipal water treatment

• Industrial wastewater systems

• Reverse osmosis processes

This application is especially important in industrial facilities across Africa where water reuse and treatment efficiency are priorities.

Mining and Industrial Processing

In mining, sodium metabisulphite is used as a flotation reagent, particularly in gold processing, where it helps control oxidation and improve mineral separation.

Grades and Specifications to Consider

When sourcing sodium metabisulphite, buyers should pay close attention to:

• Grade: Food grade, industrial grade, or pharmaceutical grade

• Purity level: Typically 97% or higher

• CAS number: Must be clearly stated as 7681-57-4

• Packaging: Usually 25kg bags or bulk packaging

• Shelf life and storage conditions

Incorrect grade selection can lead to compliance issues or product failure. This is where working with an experienced supplier matters.

Challenges in Sourcing Sodium Metabisulphite

Businesses often face challenges such as:

• Inconsistent quality between suppliers

• Missing or incorrect documentation

• Supply chain delays

• Non-compliance with local regulations

For African importers and distributors, logistics coordination and regulatory alignment are just as important as price.

Wigmore Trading can help by sourcing verified sodium metabisulphite from reputable manufacturers and managing documentation, shipping, and compliance requirements.

Why Source Sodium Metabisulphite Through Wigmore Trading?

Wigmore Trading supports businesses across Africa with reliable chemical sourcing and international trade expertise. When sourcing sodium metabisulphite, Wigmore Trading offers:

• Verified products with correct CAS numbers

• Access to food-grade and industrial-grade supply

• Full SDS and compliance documentation

• End-to-end logistics and customs support

• Market knowledge across FMCG, mining, and industrial sectors

Rather than navigating fragmented supplier networks, businesses can streamline sourcing through a single trusted partner.

Contact Wigmore Trading today to streamline your chemical sourcing and distribution needs.

Conclusion

Understanding the sodium metabisulphite CAS No (7681-57-4) is essential for safe use, regulatory compliance, and efficient procurement. Whether used in food processing, water treatment, or industrial applications, sourcing the correct grade from a reliable supplier is critical.

With its experience in global sourcing and African trade logistics, Wigmore Trading can help businesses secure high-quality sodium metabisulphite with confidence.

Get in touch with our team to learn more about sourcing sodium metabisulphite for your industry.