Mono Propylene Glycol (MPG)
Versatile, low-toxicity organic compound - wide range of applications from cosmetics to food, pharmaceuticals to industry
Overview
Mono Propylene Glycol (MPG, CAS No: 57-55-6), is a colorless, odorless, slightly sweet-tasting liquid. This dihydric alcohol produced by hydration of propylene oxide is completely soluble in water and miscible with most organic solvents. Due to its low toxicity and versatility, it has a wide range of industrial applications.
MPG is an excellent humectant and solvent due to its hygroscopic properties. FDA, USP and EP grade versions are available for pharmaceutical and food applications. It is widely used in cosmetics, pharmaceuticals, food, animal feed and industrial applications.
Applications
Mono Propylene Glycol has a wide range of industrial and consumer applications:
Cosmetics and Personal Care
Used as a humectant, solvent and carrier in creams, lotions, deodorants, shampoos and makeup products.
Pharmaceuticals
Used as a solvent, stabilizer and carrier in drug formulations. Found in oral, topical and injectable preparations.
Food Additive
Used as a humectant, solvent and flavor carrier in food products with E1520 code. FDA GRAS status.
E-Cigarette Liquids
One of the main components of e-liquids used in vapor production and flavor carrying.
Antifreeze and Heat Transfer
Used in low-toxicity antifreeze formulations, food processing equipment and HVAC systems.
Animal Feed
Used as a humectant and energy source in animal feed. Particularly common in dairy farming.
Paints and Coatings
Used as a solvent, coalescent and freeze-thaw stabilizer in water-based paints. Improves film formation.
Polymer Production
Used as a monomer in the production of polyester resins, polyurethanes and other polymers.
Technical Specifications
| Property | Value | Unit | Test Method |
|---|---|---|---|
| Chemical Formula | C₃H₈O₂ | - | - |
| CAS Number | 57-55-6 | - | - |
| EC Number | 200-338-0 | - | - |
| Molecular Weight | 76.10 | g/mol | - |
| Appearance | Colorless, clear liquid | - | Visual |
| Odor | Slightly sweet, characteristic | - | Olfactometry |
| Density (20°C) | 1.036-1.040 | g/cm³ | ASTM D4052 |
| Boiling Point | 187.6 | °C | ASTM D1078 |
| Melting Point | -60 | °C | ASTM D1015 |
| Flash Point | 99 | °C | ASTM D93 |
| Autoignition Temperature | 421 | °C | ASTM E659 |
| Vapor Pressure (20°C) | 0.016 | kPa | ASTM D2879 |
| Viscosity (20°C) | 56 | cP | ASTM D445 |
| Solubility in Water | Completely miscible | - | ASTM D1720 |
| pH Value (20°C) | 6.5-7.5 | - | ASTM E70 |
| Purity (GC) | ≥99.5 | % | ASTM D3545 |
| Water Content | ≤0.1 | % | ASTM E203 |
| Acidity (as acetic acid) | ≤0.005 | % | ASTM D1613 |
| Color (Pt-Co) | ≤10 | APHA | ASTM D1209 |
| Carbonyl (as acetaldehyde) | ≤0.005 | % | ASTM D2191 |
Safety Information
Hazard Symbols and Statements
Low Hazard Eye Irritation
Personal Protective Equipment (PPE)
- Chemical-resistant gloves (nitrile or neoprene)
- Chemical safety goggles or face shield (for high splash risk)
- General ventilation is sufficient, local exhaust not required
- Protective apron or work clothes (for prolonged contact)
- Use organic vapor filter respirator for high temperature applications
Storage Conditions
- Store in cool, dry, well-ventilated area
- Protect from excessive heat and direct sunlight
- Store in stainless steel, polyethylene or glass containers
- Store separately from oxidizing agents
- Storage temperature: 10-30°C
- No special moisture protection measures required
Fire Fighting
- Suitable extinguishing media: Water spray, dry chemical, CO₂, foam
- May form flammable vapors at high temperatures
- Use appropriate respiratory protection during fire fighting
- Use dry chemical or CO₂ for small fires
- Use water spray or alcohol-resistant foam for large fires
- Cool containers with water during fire fighting
Handling and Storage
Handling
- Ensure containers are tightly closed during transport
- Provide adequate ventilation in transport vehicles
- Avoid eating, drinking or smoking during handling
- Proper labeling required on transport containers
- Grounding to prevent static electricity buildup
- Use appropriate packaging to prevent spills
Storage
- Store in stainless steel, polyethylene or glass containers
- Provide appropriate signage in storage area
- Use appropriate breathing vents on storage tanks
- Provide secondary containment measures for large quantities
- Prohibit smoking in storage areas
- Store separately from acids and oxidizers
- Provide spill control equipment in storage areas
Spill Response Measures
- Isolate the spill area
- Use appropriate protective equipment
- Absorb spills with sand, chemical absorbent or other absorbent materials
- Dispose of absorbed material appropriately
- Wash spill area with plenty of water and detergent
- Call professional cleaning service for large spills
- Prevent spills from entering sewers or water sources
Regulatory Information
GHS Classification
- Skin Irritation Category 2
- Eye Irritation Category 2A
- Specific Target Organ Toxicity (Single Exposure) Category 3
Important Regulations
- REACH: Registered
- CLP: Compliant
- FDA: GRAS status under 21 CFR 184.1666
- EFSA: Approved as food additive (E1520)
- USP: Pharmaceutical grade specifications available
- EP: European Pharmacopoeia compliant
International Legislation
- European Union: Subject to Directive 2008/58/EC
- USA: Compliant with FDA and EPA regulations
- China: Listed in IECSC
- Japan: Listed in ISHL
- Global: Evaluated by JECFA
- IMO: Not classified as marine pollutant
Environmental Information
Environmental Impact
Mono Propylene Glycol degrades rapidly in the environment (>90% within 28 days). When mixed with water sources, it shows low toxicity to aquatic organisms. It degrades rapidly in soil through biological processes. It does not deplete the ozone layer and has minimal contribution to global warming.
Biological Degradation
- Air: 1-3 day half-life through photochemical reactions
- Water: Complete degradation within 7-14 days through microbial activity
- Soil: Rapid degradation through microbial activity
- Biological Oxygen Demand (BOD): 1.0-1.2 g O₂/g MPG
- Chemical Oxygen Demand (COD): 1.5-1.7 g O₂/g MPG
Waste Management
- Not classified as hazardous waste
- Small quantities can be disposed through biological treatment in licensed facilities
- Large quantities should be incinerated in licensed hazardous waste disposal facilities
- Dispose according to local regulations
- Prevent entry into wastewater
- Prevent seepage into soil and groundwater
Frequently Asked Questions
How is Mono Propylene Glycol produced?
MPG is mainly produced by two methods: 1) Hydration of propylene oxide with water, 2) Catalytic hydrogenolysis of glycerol. Industrial-scale continuous distillation processes are used with annual global production exceeding 2 million tons.
What is the difference between Mono Propylene Glycol and Diethylene Glycol?
MPG (C₃H₈O₂) is a single propylene glycol molecule, while Diethylene Glycol (DEG, C₄H₁₀O₃) is formed by the combination of two ethylene glycol molecules. MPG has lower toxicity and is widely used in food/pharmaceutical applications, while DEG is preferred for industrial applications.
Is Mono Propylene Glycol safe for use in food?
Yes, it has FDA "Generally Recognized as Safe" (GRAS) status and is used as a food additive with E1520 code. Acceptable Daily Intake (ADI) has not been specified, meaning reasonable consumption is safe.
What is the shelf life of Mono Propylene Glycol?
When stored in properly sealed containers, MPG has a shelf life of approximately 2 years. It should be tightly closed to prevent moisture absorption and oxidation. Stability testing is recommended before long-term storage.
What should I do if Mono Propylene Glycol contacts my skin?
Remove contaminated clothing immediately and wash with plenty of soap and water. Prolonged contact may cause dryness to the skin. Seek medical attention if irritation persists. For eye contact, flush with plenty of water for at least 15 minutes and consult an eye doctor. If swallowed, do not induce vomiting, seek immediate medical attention.
Can Mono Propylene Glycol be mixed with other solvents?
Yes, MPG is miscible with water, alcohols, ketones, esters and most organic solvents in all proportions. It is immiscible with oils and hydrocarbons. It has excellent compatibility especially with water and ethylene glycol. However, it may react with strong oxidizers and acids.