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Chemical Name: Neutral Red
Common Usage: Staining in biological labs, cell viability testing, histology
Synonyms: C.I. 50040, Toluylene Red, Basic Red 5
Molecular Formula: C15H17ClN4
Appearance: Usually a dark red or brownish powder in concentrated form, solution tends to have a pink to red liquid color
Primary Users: Laboratory professionals in research, clinical diagnostic labs, educational institutions
GHS Classification: Eye irritant, Skin irritant, Suspected mutagen
Signal Word: Warning
Hazard Statements: Causes skin and eye irritation; may cause allergic skin reaction; may cause respiratory irritation in powdered form
Precautionary Statements: Wear gloves, avoid breathing dust, prevent contact with eyes and skin
Symptoms of Exposure: Redness, itching, tearing, sneezing, skin rashes on extended contact, mild respiratory discomfort in powder form
Active Component: Neutral Red (approx. 0.1%-1%)
Solvent: Distilled water
Other Ingredients: May include a buffer system, preservatives such as sodium azide at less than 0.1% for bacterial control
Known Contaminants: Trace levels vary based on manufacturing; reputable sources typically guarantee high purity for lab use
Skin Contact: Remove contaminated clothing. Wash affected skin with plenty of water and soap. Persistent rash or irritation calls for medical attention.
Eye Contact: Flush eyes under running water for several minutes, keeping eyelids apart. Don’t rub eyes. Seek medical help if irritation persists.
Inhalation: Move to fresh air. If symptoms appear like coughing or throat irritation, medical support might be required. Prolonged discomfort justifies further intervention.
Ingestion: Rinse mouth with water. A small accidental amount usually does not pose acute toxicity, yet medical advice is a safe route if discomfort occurs.
Suitable Extinguishing Media: Water spray, foam, carbon dioxide, dry chemical
Specific Hazards: On burning, can release toxic fumes including nitrogen oxides and carbon monoxide
Protective Equipment: Firefighters use self-contained breathing apparatus and full protective gear
Fire Behavior: Solution itself does not ignite easily; residual dried powder is more prone to fire risk
Personal Precautions: Laboratory gloves and goggles provide immediate barrier. Ventilate affected area.
Spill Cleanup: Absorb small spills with paper towels or inert material like sand; avoid direct contact; collect residue for disposal
Environmental Measures: Prevent large spills entering drains or waterways, as colored dyes can disrupt aquatic systems even at low concentrations
Safe Handling: Handle in a well-ventilated space. Minimize contact through use of pipettes, auto dispensers, or designated bottle-tipping tools. Never eat, drink or touch face after direct handling.
Storage Conditions: Store at room temperature, shielded from light, away from incompatible chemicals such as strong oxidizers. Tight sealing minimizes evaporation.
Incompatible Materials: Strong acids and bases, strong oxidizing agents
Shelf Life: Most lab preparations remain stable for months—early notice of precipitation or fading color signals the need for disposal.
Exposure Limits: No official occupational exposure limits for Neutral Red, but prudent practice requires minimizing dust inhalation
Personal Protective Equipment: Nitrile or latex gloves, chemical splash goggles, lab coat. Powder handling best done in fume hoods.
Hygiene Measures: Thorough hand washing, even after glove removal. Immediate attention to all accidental splashes.
Engineering Controls: Fume hood or local exhaust for large quantities or powdered form
State: Solution is a transparent red liquid; raw powder form is crystalline and reddish
Odor: Odorless or faint chemical smell
Solubility: Readily soluble in water; slightly soluble in ethanol
Boiling Point: Close to water (as solution)
Melting Point (Powder): Approximately 260°C with decomposition.
pH: Acidic to neutral, depending on buffer and dilution
Stability: Stable at room temperature with normal precautions
Reactivity: Stable in neutral or mildly acidic environment. Strong alkalis bleach dye rapidly.
Conditions to Avoid: High heat, direct sunlight, open flames, strong oxidizing chemicals
Hazardous Decomposition: Burning or decomposition may generate toxic nitrogen or chlorine-containing gases
Polymerization: No hazardous polymerization reported
Routes of Exposure: Skin and eye contact, inhalation of dust, accidental ingestion
Acute Effects: Irritation to skin, eyes, and mucous membranes; unlikely to cause severe toxicity in normal laboratory uses
Chronic Effects: Prolonged skin contact can lead to sensitization; data suggest potential mutagenic effects in cell cultures, though clear evidence in humans lacking
Carcinogenicity: No direct classification by IARC or OSHA; prudent to assume probable risk in case of high exposure over long periods
Environmental Effects: Releases of Neutral Red can tint waterways and persist in sediments. Dyes in small concentrations disrupt aquatic flora and fauna.
Biodegradation: Slow to degrade under natural conditions; accumulates in water or soil
Bioaccumulation: Evidence of accumulation in some aquatic species
Mobility: Highly soluble, may spread quickly in wet environments
Preferred Methods: Small lab quantities go in designated hazardous waste. Do not pour down drains.
Container Disposal: Rinse and dispose of in accordance with local or institution-specific hazardous waste routines
Regulations: Most local and federal pollution guidelines classify Neutral Red dye solutions as hazardous laboratory waste
Shipping Class: Most dilute solutions are not regulated in small containers, but large shipments may fall under hazardous substances
Packaging: Leak-proof, clearly labeled container, resilient to breakage
Special Transport Precautions: Avoid package punctures, protect against tilting or crushing
Labeling Requirements: Hazard pictograms for irritant; clear symbols alerting to potential mutagenic risk
Lab Safety Rules: Adequate documentation in chemical inventory; annual safety reviews mandatory in most academic labs
Global Harmonization: SDS compliance with GHS for hazard symbols and precaution statements
Environmental Regulations: Wastewater regulations may require pre-treatment before disposal, as dyes impact municipal treatment processes
