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E151, also known as Black PN, is a dark synthetic colorant that falls under the category of azo dyes.
It is often used to give a black or deep purple color to food, beverages, and cosmetics.
Its use in food products is restricted in some countries, as it is associated with possible adverse effects.
CAS Number: 1934-21-0
Synonyms:
Black PN,Acid Black 1,CI 20470,E151 Food Dye,Solvent Black 1
Introduction
E151, also known as Black PN or Brilliant Black BN, is a synthetic azo dye widely used as a food colorant.
It is identified by the European food additive number E151 and the Colour Index number 28440.
The primary function of E151 is to impart a deep black hue to food and non-food products.
It is particularly utilized in products where natural black colorants are either unavailable or unstable.
Historically, synthetic dyes like E151 were developed in the early 20th century to overcome the limitations of natural colorants in terms of stability, intensity, and cost.
E151 was first synthesized and introduced as a commercial dye in the mid-1900s.
Since then, its applications have broadened to include various industries beyond food.
Chemical Properties
Chemical Name: Tetrasodium 4-acetamido-5-hydroxy-6-[[7-sulfonato-4-[(4-sulfonatophenyl)azo]-1-naphthyl]azo]naphthalene-1,7-disulfonate
Molecular Formula: C28H17N5Na4O14S4
Molecular Weight: 869.68 g/mol
Appearance: Black powder or granules
Solubility: Soluble in water; insoluble in organic solvents
pH Range: Stable in acidic and neutral conditions; color fades in highly alkaline conditions
The structure of E151 consists of multiple azo (-N=N-) groups linking aromatic rings, contributing to its intense coloration and chemical stability.
It is highly water-soluble due to the presence of multiple sulfonate groups.
Synthesis and Manufacturing
E151 is synthesized via a multi-step process involving diazotization and azo coupling reactions.
The process generally includes:
Diazotization of aromatic amines under acidic conditions.
Coupling with naphthalene derivatives containing sulfonic acid groups.
Neutralization with sodium salts to increase solubility.
Raw materials include:
Aniline derivatives
Naphthol or naphthylamines
Sulfonating agents (e.g., sulfuric acid)
Quality control is essential to ensure purity and the absence of toxic by-products such as aromatic amines.
Applications
Food Industry: Used in confectionery, desserts, flavored beverages, licorice, sauces, and decorative icings.
Pharmaceuticals: Coloring agent in tablets, syrups, and topical preparations.
Cosmetics: Present in shampoos, hair dyes, and lotions.
Industrial: Used in inks, textiles, and paper products.
The appeal of E151 lies in its deep black coloration and resistance to light and heat degradation.
Regulations and Legislation
European Union: Permitted in specific food categories with clear labeling requirements
United States: Not approved; considered unfit for food use
Codex Alimentarius: Allows use under specified conditions
Labeling must include its name or E-number and declaration of its synthetic origin in some jurisdictions.
Analytical Methods
Detection and quantification techniques include:
High Performance Liquid Chromatography (HPLC)
Spectrophotometry (UV-Vis)
Mass Spectrometry (MS)
These methods help ensure product compliance and traceability, particularly in regulatory contexts and food safety investigations.
Benefits and Functional Role
E151 is valued for:
High coloring strength
Stability across pH and temperature ranges
Cost-effectiveness compared to natural alternatives
Its use can improve product aesthetics and consumer appeal, especially in confectionery and decorative foods.
Environmental Impact
Biodegradability: Poorly biodegradable; can persist in aquatic systems
Waste Management: Requires advanced treatment methods such as activated carbon adsorption and advanced oxidation
Ecotoxicity: Potentially harmful to aquatic life at high concentrations
Efforts are ongoing to improve waste treatment practices in dye manufacturing industries.
Consumer Perception and Market Trends
Consumer skepticism about synthetic dyes has led to:
Increased demand for natural alternatives
Product reformulation in favor of clean-label ingredients
Controversies over health effects and bans in certain regions
Despite this, E151 remains popular in countries with established safety regulations and high-volume production.
Alternatives and Substitutes
Possible alternatives to E151 include:
Carbo vegetabilis (activated carbon): Used in some natural food products
Black carrot extract: Natural black colorant with antioxidant properties
Iron oxides: Approved for use in non-food applications
Natural alternatives often lack the stability and intensity of synthetic dyes, presenting challenges for formulators.
Conclusion and Future Outlook
E151 Black PN remains a prominent synthetic dye with broad applications due to its intensity and stability.
While concerns over health and environmental impact persist, regulatory bodies have provided usage guidelines to mitigate risks.
Future developments may focus on:
Safer synthetic processes
Improved waste management
Development of stable natural alternatives
As consumer demand evolves, the role of E151 in food and non-food industries will likely be shaped by technological innovations and regulatory shifts.
SAFETY INFORMATION ABOUT E 151 BLACK PN
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
