Sodium Nitrate, Chile Saltpeter, Soda Niter, Nitratine, Sodium Saltpeter, Cubic Niter, E251, 7631-99-4

SODIUM NITRATE (NaNO₃, E251)

1. Chemical Identity and Material Classification

• Chemical Name: Sodium Nitrate, Nitric Acid Sodium Salt

• Synonyms: Chile Saltpeter, Soda Niter, Nitratine, Sodium Saltpeter, Cubic Niter

• CAS Number: 7631-99-4

• EC Number (EINECS): 231-554-3

• Molecular Formula: NaNO₃

• Molecular Weight: 84.995 g/mol

• E Number: E251 (food additive)

• Chemical Class: Inorganic nitrate salt (oxidizing agent)

• HS Code: 3102.50

• UN Number: 1498 (Sodium nitrate, 5.1)

2. Physical Properties

2.1 General Physical Properties

2.2 Temperature-Dependent Solubility in Water

2.3 Solubility in Other Solvents

2.4 Aqueous Solution Properties

3. Chemical Properties

3.1 Molecular Structure

Structure: Na⁺ NO₃⁻

• Ionic crystal (sodium cations, nitrate anions)

• Strong oxidizing agent (contains nitrogen in +5 oxidation state)

• Nitrate ion (NO₃⁻) is planar trigonal

3.2 Thermal Decomposition

3.3 Chemical Reactivity

3.4 Oxidizing Properties

3.5 Stability

3.6 Incompatibilities

4. Quality Specifications

4.1 Technical / Industrial Grade

4.2 Food Grade (E251 – FCC / USP)

4.3 Agricultural Grade (Fertilizer)

5. Production Methods

5.1 Natural Mining (Chile Saltpeter – Historical)

Source: Natural deposits in northern Chile (Atacama Desert)

Process: Crushing → dissolution → crystallization → purification

Current status: Limited production; largely replaced by synthetic processes

5.2 Synthetic Production – Nitric Acid Neutralization (Most Common)

Reaction: HNO₃ (nitric acid) + NaOH (sodium hydroxide) → NaNO₃ + H₂O

Process:

1. Nitric acid is neutralized with sodium hydroxide or sodium carbonate

2. Solution concentrated by evaporation

3. Crystallization

4. Drying

Alternative: Na₂CO₃ + 2HNO₃ → 2NaNO₃ + H₂O + CO₂

5.3 Absorption of Nitrogen Oxides

Process: Absorption of NOₓ gases in sodium hydroxide or sodium carbonate solution

Reaction: NO + NO₂ + 2NaOH → 2NaNO₂ + H₂O (primarily nitrite, then oxidized to nitrate)

6. Mechanism of Action (Food Preservation – E251)

6.1 Antimicrobial Mechanism

• Sodium nitrate itself has limited antimicrobial activity

• Bacterial reduction (by Micrococcus, Lactobacillus, Staphylococcus) converts nitrate (NO₃⁻) to nitrite (NO₂⁻)

• Nitrite further converts to nitric oxide (NO) under acidic conditions (meat pH ~5.5–6.0)

• Nitric oxide reacts with iron-sulfur proteins and heme iron in bacteria

• Disrupts bacterial electron transport and metabolism

• Specifically effective against Clostridium botulinum (botulism prevention)

6.2 Color Fixation (Curing)

• Nitric oxide (NO) reacts with myoglobin → nitrosomyoglobin (pink-red color)

• Heat-stable pink color characteristic of cured meats (ham, bacon, sausages)

6.3 Antioxidant (Lipid Oxidation Prevention)

• Nitric oxide (NO) acts as a radical scavenger

• Prevents lipid oxidation (rancidity) in cured meats

• Extends shelf life

7. Industrial Applications

7.1 Agriculture (Fertilizer) – Largest Application (~60–70%)

Benefits:

• Highly soluble nitrogen source

• Rapid plant uptake (nitrate form is immediately available)

• Ideal for chlorine-sensitive crops (potatoes, tobacco, citrus, berries)

• No soil acidification (unlike ammonium-based fertilizers)

7.2 Food Industry (E251) – Curing and Preservation

Regulatory limits (EU, US, Codex):

• Added alone or with nitrite: max 150–300 mg/kg (varies by product)

• Residual nitrate in finished product: typically <200 mg/kg

Important safety note: Nitrate is converted to nitrite in the product; nitrite is the active antimicrobial species. Use limited to prevent nitrosamine formation.

7.3 Explosives and Pyrotechnics (~10–15%)

7.4 Glass and Ceramic Industry

7.5 Metallurgy and Metal Treatment

7.6 Chemical Industry

7.7 Pharmaceuticals

7.8 Water Treatment

8. Toxicology and Safety

8.1 Acute Toxicity

8.2 Chronic Toxicity

8.3 Methemoglobinemia (Blue Baby Syndrome)

8.4 GHS Classification

8.5 NFPA Rating

UN Classification: 5.1 (Oxidizing substance)

UN Number: 1498 (Sodium nitrate)

9. Safety Precautions and Personal Protective Equipment (PPE)

• Hazards:

  • Strong oxidizer (H272) – Contact with combustible material may cause fire

  • Harmful if swallowed (H302)

  • Causes serious eye irritation (H319)

  • Non-combustible but accelerates burning of combustible materials

  • May form explosive mixtures with reducing agents (metal powders, charcoal, sulfur, ammonium salts under heat)

• PPE (recommended – industrial handling):

  • Safety glasses (EN 166) or chemical goggles – mandatory (eye hazard)

  • Dust mask (FFP2/N95) – for dusty operations

  • Chemical-resistant gloves (nitrile)

  • Protective clothing (dust protection)

  • Fire-resistant clothing when handling large quantities

• Engineering controls:

  • Local exhaust ventilation (LEV) for dust control

  • Keep away from combustible materials, reducing agents

  • Grounding to prevent static discharge

  • Eyewash stations and safety showers

• Storage conditions:

  • Store in tightly closed original container (HDPE, PP, lined steel)

  • Keep away from combustible materials (wood, paper, oil, grease, organic matter)

  • Store away from reducing agents (metal powders, charcoal, sulfur, hydrides)

  • Store in cool, dry, well-ventilated area

  • Separate from acids (NOₓ gas evolution)

  • Protect from moisture (slightly hygroscopic)

• Firefighting:

  • Use water fog or spray (DO NOT use dry chemical, CO₂, or foam – may not suppress)

  • Flood with water; large amounts of water recommended

  • Wear full protective clothing and SCBA

  • Move containers away from fire if possible

• First aid:

  • Inhalation: Move to fresh air; if breathing difficult, give oxygen; if stopped, give artificial respiration; seek medical attention

  • Eye contact: Rinse with water for at least 15 minutes, lifting eyelids; remove contact lenses; seek medical attention

  • Skin contact: Wash with soap and water

  • Ingestion: Rinse mouth; do NOT induce vomiting; drink water; seek medical attention (methemoglobinemia risk with large doses)

10. Environmental Fate

11. Storage and Shelf Life

11.1 Storage Conditions

11.2 Shelf Life

12. Transport Information

13. Synonyms and Common Names

• English: Sodium Nitrate, Chile Saltpeter, Soda Niter, Nitratine, Sodium Saltpeter, Cubic Niter

• Trade names: Nitratina, Soda Nitre

• Spanish: Nitrato de sodio, Salitre

• German: Natriumnitrat

• French: Nitrate de sodium

• Turkish: Sodyum Nitrat

14. Regulatory Status

15. Why Choose Sodium Nitrate?

Limitations:

• Strong oxidizer – Fire hazard when in contact with combustible materials

• Health concerns (nitrosamines) – Limited use in food; strict regulations

• Methemoglobinemia risk – Especially in infants; drinking water limits apply

• Eutrophication potential – Nitrogen runoff contributes to algal blooms

• Not organic – Not permitted in certified organic production

16. Comparison with Other Nitrates

17. Sodium Nitrate vs. Sodium Nitrite – Key Differences

18. Frequently Asked Questions (FAQs)

Q1: Is sodium nitrate safe to eat?
A1: Yes, at regulated levels (E251). Sodium nitrate is used as a curing agent in meats (ham, bacon, sausages) to prevent botulism and preserve color. However, high intake may form nitrosamines (potential carcinogens). Regulatory limits apply.

Q2: Is sodium nitrate the same as sodium nitrite?
A2: No. Sodium nitrate (NaNO₃) has nitrogen in +5 oxidation state; sodium nitrite (NaNO₂) has nitrogen in +3 oxidation state. Nitrate is less toxic and must be converted to nitrite by bacteria to be active as a food preservative.

Q3: Why is sodium nitrate used in fertilizers?
A3: It provides immediately available nitrogen (16% N) that plants can absorb directly (nitrate form). It is chlorine-free, non-acidifying, and ideal for chlorine-sensitive crops (potatoes, tobacco, citrus, berries).

Q4: Can sodium nitrate explode?
A4: No. Sodium nitrate itself does not explode. However, when mixed with combustible materials (charcoal, sulfur, metal powders, organic matter), it forms pyrotechnic or explosive mixtures (black powder substitute, fireworks).

Q5: Is sodium nitrate bad for the environment?
A5: Excess nitrate runoff from fertilizers can cause eutrophication (algal blooms) in water bodies. However, sodium nitrate is highly water-soluble and does not bioaccumulate.

19. Storage Recommendations

20. Summary Table – Key Specifications at a Glance

This TDS is prepared in compliance with ISO 11014-1 format and is intended for agricultural specialists, food technologists, pyrotechnicians, glass manufacturers, metallurgists, chemical engineers, and procurement professionals. Certificates of Analysis (CoA), Safety Data Sheets (SDS), and sample validation reports are available upon request.