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IUPAC Name: Disodium hydrogen phosphate
Chemical Formula: Na₂HPO₄
Common Names: Disodium phosphate, DSP, Sodium phosphate dibasic anhydrous
Pharmaceutical Names: Natrii phosphas dibrasicus anhydricus
Food Additive Designation: E339(ii)
CAS Registry Number: 7558-79-4
EC Number: 231-448-7
UNII: 22ADO53M6F
Molecular Architecture:
Molecular Formula: Na₂HPO₄
Molar Mass: 141.96 g/mol
Crystal System: Orthorhombic (for anhydrous form)
Space Group: Pnma
Unit Cell Parameters: a = 6.81 Å, b = 8.23 Å, c = 4.92 Å
Coordination: Sodium ions octahedrally coordinated by oxygen atoms
Extended Physical Characterization:
Anhydrous dibasic sodium phosphate is a white, crystalline, odorless powder. It exists in several hydrated forms (di-, hepta-, dodecahydrate), with the anhydrous form being the most stable under low humidity conditions. The compound is hygroscopic and will absorb moisture from air to form hydrates.
Physical Property Data:
Appearance: White crystalline powder
Odor: Odorless
Taste: Saline, slightly bitter
Density: 1.52 g/cm³ (X-ray density)
Melting Point: Decomposes at 240°C (loses water to form Na₄P₂O₇)
Solubility in Water:
0°C: 71 g/L
20°C: 120 g/L
40°C: 188 g/L
60°C: 268 g/L
80°C: 358 g/L
100°C: 463 g/L
pH (1% solution): 8.0-9.0 (varies with concentration)
Hygroscopicity: Absorbs moisture up to ~5% at 50% RH
Refractive Index: 1.436-1.438
Thermal Conductivity: ~1.0 W/m·K
Chemical Behavior and Buffer Properties:
Buffer Characteristics:
pKa₂ of phosphoric acid: 7.20 at 25°C
Effective buffer range: pH 6.2-8.2
Buffer capacity: Maximum at pH = pKa = 7.20
Ionic strength effects: Buffer capacity increases with concentration
Common Buffer Systems:
Phosphate Buffered Saline (PBS): Na₂HPO₄ + NaH₂PO₄ + NaCl
Sørensen's phosphate buffer: Varying ratios of Na₂HPO₄ and KH₂PO₄
Dulbecco's PBS: Modified PBS for cell culture
Chemical Reactivity:
Acid-base reactions: Forms monosodium or trisodium phosphate
Precipitation reactions: With divalent cations (Ca²⁺, Mg²⁺, Zn²⁺)
Thermal decomposition: To sodium pyrophosphate (Na₄P₂O₇)
Complex formation: With various metal ions
Industrial Applications:
Pharmaceutical Applications:*
Buffer agent: In parenteral, ophthalmic, and oral formulations (0.1-2.0%)
Laxative: Component of phosphate enemas and oral laxatives
Electrolyte replenisher: In oral rehydration solutions
Excipient: Tablet disintegrant and pH adjuster
Food Industry (as E339ii):*
Emulsifying salt: In processed cheeses and dairy products (0.5-3.0%)
Acidity regulator: In beverages and baked goods
Mineral supplement: Source of phosphorus
Water retention agent: In meat and seafood products
Industrial Applications:*
Water treatment: Corrosion inhibitor and scale preventer
Detergent builder: In cleaning formulations
Textile processing: Scouring agent and dyeing assistant
Metal treatment: Surface preparation and corrosion protection
Analytical Characterization:
Quality Control Tests:
Identification: IR spectroscopy matches reference spectrum
pH: 8.0-9.0 (1 in 100 solution)
Loss on drying: ≤2.0% (105°C for 4 hours)
Heavy metals: ≤0.001%
Arsenic: ≤0.0003%
Chloride: ≤0.05%
Sulfate: ≤0.05%
Quantitative Analysis:
Assay: Titration with 0.1M HCl using potentiometric endpoint (98.0-101.0%)
Phosphate content: Gravimetric as ammonium phosphomolybdate
Sodium content: Flame photometry or atomic absorption
Instrumental Methods:
X-ray diffraction: For crystalline form identification
Thermal analysis: TGA for hydrate determination
Ion chromatography: For impurity profiling
SAFETY INFORMATION ABOUT ANHYDROUS DIBASIC SODIUM PHOSPHATE
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
