POTASSIUM NITRATE

CAS Number: 7757-79-1
 Synonyms: E252; Nitric acid potassium salt; Saltpeter; Niter; Saltpetre (historical); Nitrate of potash; Kaliumnitrat (German); Nitrato de potasio (Spanish); Niter (mineral form)
Physical Properties:
Appearance: White to colorless prismatic crystals or crystalline powder (odorless, cooling saline taste).
Solubility: Moderately soluble in water (approx. 31.6 g/100 mL at 20°C; 247 g/100 mL at 100°C); very slightly soluble in ethanol (negligible); slightly soluble in glycerol.
Molecular weight: 101.10 g/mol.
Melting point: 334°C (decomposes at ~400°C to potassium nitrite and oxygen).
Density: 2.109 g/cm³.
pH (5% solution): 6.5–7.5 (neutral).
Hygroscopicity: Very low (does not absorb significant moisture from air; much less deliquescent than sodium nitrate or nitrites).
Oxidizing properties: Strong oxidizer when molten or heated; supports rapid combustion; forms explosive mixtures with organic matter, charcoal, sulfur, and metals.
Applications:
Cured meat and cheese (E252): Dry-cured hams (especially Serrano, Iberian, Parma, Prosciutto), dry sausages (Spanish chorizo, Italian salami), dry-cured bacon, corned beef, and deli meats. In cheese: Emmental, Gruyère, Gouda, Edam, and other Swiss-type cheeses.
Cheese specific: Prevents late blowing in cheeses where sodium nitrate (E251) is undesirable due to sodium content or taste interference.
Pharmaceuticals: Ingredient in desensitizing toothpaste for sensitive teeth (e.g., potassium nitrate 5% blocks dentinal tubules, reducing nerve conduction). Also in antihypertensive formulations (rare).
Industrial (major use): Component of black powder/gunpowder (75% KNO₃, 15% charcoal, 10% sulfur) – historically the first chemical explosive; present-day pyrotechnics (fireworks, rocket motors, smoke bombs, model rocket engines), blasting agents (ANFO substitute), fertilizer (potassium-rich source), heat transfer salt (CSP plants with NaNO₃).
Food preservation: Historically used for preserving meat before refrigeration (saltpeter mixed with salt).
Laboratory: Strong oxidizing agent for organic synthesis, nitration reactions, and preparation of potassium nitrite.
Food storage: In some brine recipes for pickles and corned meats.
Description:
 Potassium nitrate (E252) is a naturally occurring mineral salt (niter/saltpeter) that, like sodium nitrate (E251), serves as a slow-release nitrite source for cured meats, fish, and certain cheeses. Its use as a food additive is almost identical to sodium nitrate, with two key differences: (1) Potassium nitrate provides potassium ion (K⁺) instead of sodium, making it suitable for low-sodium and "reduced sodium" cured meats where sodium chloride (regular salt) is also lowered; (2) Potassium nitrate is less soluble than sodium nitrate (31.6 g/100 mL vs. 88 g/100 mL at 20°C), which can affect brine concentration rates in some curing processes. Historically, saltpeter was the primary agent for preserving meat long before refrigeration, often in the form of "saltpetered" or "corned" beef (where "corned" refers to the coarse salt + saltpeter crystals). In modern practice, potassium nitrate is still used for premium dry-cured hams and sausages where traditional recipes are followed. For example, Parma ham (Prosciutto di Parma) traditionally uses sea salt with small amounts of potassium nitrate (up to 250 ppm). The nitrate is converted to nitrite by the natural bacterial flora during the 12-24 month aging process. This conversion yields a deep red color and characteristic flavor while ensuring residual nitrite levels at consumption are extremely low (<10 ppm). Potassium nitrate adds no undesirable taste at these levels. In cheese production, potassium nitrate is preferred over sodium nitrate (E251) for certain European Protected Designation of Origin (PDO) cheeses because it does not contribute sodium, and the potassium ion may influence starter culture metabolism and cheese texture. The safety profile of potassium nitrate is similar to sodium nitrate: low acute toxicity (oral LD₅₀ in rats ~ 3750 mg/kg), but concerns about reduction to nitrite and subsequent nitrosamine formation apply. The ADI for potassium nitrate (as nitrate ion) is 0–3.7 mg/kg bw/day (same as sodium nitrate). For consumers, the most relevant exposure difference is the sodium contribution: using potassium nitrate instead of sodium nitrate reduces added sodium by about 25% per gram of additive (because KNO₃ contains ~38% potassium and no sodium, whereas NaNO₃ contains ~27% sodium). In a typical dry-cured ham containing 100 mg/kg nitrate, the sodium saved is negligible (27 mg sodium/kg meat). But in products with higher nitrate levels (e.g., 500 mg/kg in some Traditional Speciality Guaranteed products), sodium saved can become meaningful. Outside of food, potassium nitrate is famous as the oxidizing component of black powder (gunpowder), first formulated in 9th-century China. When heated, KNO₃ decomposes: 2 KNO₃ + heat → 2 KNO₂ + O₂; the released oxygen rapidly oxidizes the charcoal (carbon) and sulfur, producing hot gases (CO₂, SO₂, N₂) that expand and propel projectiles. While black powder is obsolete for military use (replaced by smokeless powders), it remains the standard for fireworks, hobby rockets, and reenactment cannons. In the European Union, E252 is permitted for use in dry-cured meat products (up to 150 mg/kg expressed as residual nitrite? Actually regulated as nitrate residue limits vary by country). The EFSA re-evaluation (2017) confirmed that nitrate intake from food additives does not exceed safe levels for most populations, except for some children with high processed meat consumption. Unlike nitrites (E249/E250), nitrates themselves are not directly toxic; their hazard stems only from conversion to nitrite. For this reason, some regulators (e.g., Canada) permit nitrate without strict ADI provided labeling is clear. Nevertheless, consumer pressure has reduced nitrate use in many products, often replaced by celery juice concentrate (which is naturally high in nitrate). As with nitrites, the "clean label" celery alternative produces identical nitrate residues, making the substitution largely semantic. Potassium nitrate also has medical uses: in toothpaste (5% concentration), it reduces dentin hypersensitivity by depolarizing nerve endings in the dental pulp and blocking pain transmission. The FDA has approved potassium nitrate toothpaste as effective for sensitive teeth (e.g., Sensodyne, Colgate Sensitive Pro-Relief). The amount of potassium nitrate ingested from toothpaste (swallowed residue) is negligible compared to food exposure.

SAFETY INFORMATION ABOUT POTASSIUM POTASSIUM NITRATE 

First aid measures:
Description of first aid measures:
General advice:
Consult a physician. 
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
 
If inhaled:
If breathed in, move person into fresh air. 
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately. 
Wash off with soap and plenty of water.
Consult a physician.
 
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
 
If swallowed:
Do NOT induce vomiting. 
Never give anything by mouth to an unconscious person. 
Rinse mouth with water. 
Consult a physician.
 
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
 
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment. 
 
Avoid breathing vapours, mist or gas. 
Evacuate personnel to safe areas.
 
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
 
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste. 
Keep in suitable, closed containers for disposal.
 
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
 
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place. 
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
 
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
 
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles. 
Faceshield (8-inch minimum). 
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
 
Skin protection:
Handle with gloves. 
Gloves must be inspected prior to use. 
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product. 
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. 
Wash and dry hands.
 
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
 
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls. 
 
If the respirator is the sole means of protection, use a full-face supplied air respirator. 
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so. 
Do not let product enter drains.
Discharge into the environment must be avoided.
 
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions. 
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
 
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company. 
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product