Sodium Metabisulfite (Na₂S₂O₅)

Overview

Sodium Metabisulfite (Na₂S₂O₅, CAS No: 7681-57-4) is an inorganic compound in white or slightly yellowish powder form. It finds widespread use as a preservative and antioxidant in the food industry (E223), disinfectant in water treatment systems and bleaching agent in the textile industry.

Sodium metabisulfite converts to sodium bisulfite (NaHSO₃) when dissolved in water and releases sulfur dioxide (SO₂). This property inhibits microbial growth and prevents oxidation. In food applications, it is effective in color preservation and preventing enzymatic browning.

Applications

Sodium Metabisulfite has a wide range of industrial, food and commercial applications:

Technical Specifications

Safety Information

Hazard Symbols and Statements

Toxic Corrosive Environmental Hazard

Personal Protective Equipment (PPE)

• Dust mask (N95 or equivalent)
• Chemical-resistant gloves (nitrile or neoprene)
• Protective goggles or face shield
• Lab coat or protective clothing
• Respirator in dusty environments

Storage Conditions

• Store in a cool, dry and well-ventilated place
• Keep in original packaging, tightly closed
• Storage temperature: 15-25°C
• Keep away from acids and oxidants
• Protect from moisture, prevent water contact

Fire Fighting

• Non-combustible substance but decomposes at high temperatures
• May release toxic gases (sulfur dioxide) when heated
• Suitable methods: Water spray, dry chemical powder, CO₂
• Firefighting personnel must use full respiratory protection
• Use water cautiously (solution is corrosive)

Handling and Storage

Transportation

• Ensure containers are tightly closed
• Prevent moisture contact
• Transport separately from acids and oxidants
• Have absorbent material available for spills
• Provide ventilation during transport
• Minimize dust formation

Storage

• Store in dry, cool and well-ventilated areas
• Display appropriate signage in storage area
• Protect from direct sunlight
• Store on elevated shelves
• Storage temperature should not exceed 30°C
• Keep in low humidity environments

Spill Response Measures

• Evacuate exposed personnel from area
• Use appropriate personal protective equipment
• Collect spill by dry method (sweeping)
• Do not use water - may form corrosive solution
• Wash spilled area with plenty of water (after dry collection)
• Dispose of waste appropriately

Regulatory Information

GHS Classification

• Acute Toxicity (Oral) Category 4
• Skin Irritation Category 2
• Eye Irritation Category 2A
• Respiratory Irritation Category 2
• Acute Aquatic Hazard Category 1

Important Regulations

• REACH: Registered
• EPA: Listed in TSCA inventory
• European Food Additives Regulation: Approved as E223
• FDA: GRAS (Generally Recognized As Safe) status (within limits)
• Food Codex: Maximum permitted 0.1-0.5% in certain foods

Compliance Certificates

• ISO 9001:2015 Quality Management System
• ISO 22000:2018 Food Safety Management System (for food grade)
• Kosher Certificate (for specific batches)
• Halal Certificate (for specific batches)
• Food grade certificate (for specific batches)

Environmental Information

Environmental Impact

Sodium metabisulfite can be toxic to aquatic environments at high concentrations. It consumes oxygen in water, threatening aquatic life. It decomposes rapidly in soil and does not accumulate. However, direct mixing into water sources should be prevented due to potential acidifying conditions.

Biodegradation

• Soil: Rapidly oxidized to sulfate
• Water: Converted to sulfate in presence of oxygen
• Air: May evaporate as sulfur dioxide
• Biologically degradable substance

Waste Management

• Classified as hazardous waste
• Must be neutralized before disposal
• Do not discharge to sewers or surface waters
• Dispose in accordance with local regulations
• For large amounts, work with professional waste management companies
• Use appropriate personal protective equipment during waste disposal

Frequently Asked Questions

Why is sodium metabisulfite used in foods?

Sodium metabisulfite (E223) is used in foods as preservative, antioxidant and color stabilizer. It inhibits microbial growth, prevents enzymatic browning and extends shelf life. Particularly used in dried fruits, wine and processed vegetables. Can be used at concentrations of 0.1-0.5% in foods.

Can sodium metabisulfite cause allergic reactions?

Yes, it can cause allergic reactions especially in asthmatic patients and sulfite-sensitive individuals. Symptoms such as headache, shortness of breath, skin rashes may occur in sensitive persons. Therefore, it must be indicated as E223 on food labels.

How should sodium metabisulfite be stored?

Sodium metabisulfite should be stored in a dry, cool and well-ventilated place. Protect from moisture and water. Keep in original packaging, tightly closed. Storage temperature should be 15-25°C. Keep away from acids and oxidants. Pay attention to stock rotation as decomposition may occur during long-term storage.

What is the difference between sodium metabisulfite and sodium bisulfite?

Sodium metabisulfite (Na₂S₂O₅) and sodium bisulfite (NaHSO₃) are sulfur-containing compounds with similar uses. Metabisulfite is more stable form with higher SO₂ content (65% vs 61.5%). Metabisulfite converts to bisulfite upon water contact. Metabisulfite is more commonly used in industrial applications, while bisulfite may be preferred in some food applications.

What should I do if sodium metabisulfite contacts skin?

Remove contaminated clothing immediately and wash skin with plenty of water and soap for at least 15 minutes. Seek medical attention if irritation persists. In case of eye contact, rinse eyes with plenty of water for at least 15 minutes and seek medical attention urgently. If swallowed, rinse mouth with water, do not induce vomiting and seek medical help immediately. If inhaled, move to fresh air and seek medical help if breathing difficulty occurs.