Faculty and Staff

How to Handle Picric Acid

Last updated September 4, 2009 8:55:49 PM PDT
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Follow these guidelines to protect yourself from injury when work involves picric acid.

Picric acid (C6H2(NO2)3OH), also known as trinitrophenol, is primarily used as a chemical reagent and as a booster to detonate other, less sensitive explosives, such as TNT (trinitrotoluene). Picric acid has also been used as an antiseptic, a yellow dye, and in the synthesis of a powerful insecticide.

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Obtain approval before beginning work.

Request approval from your principal investigator (PI) before beginning any new project involving picric acid.

Evaluate the hazards before beginning work.

Picric acid's explosive nature makes it one of the most hazardous substances found in the laboratory.

  • Consult safety resources available at Material Safety Data Sheet (MSDS) Sources.
  • Physical characteristics:
    • Highly sensitive to heat, shock, or friction
    • A derivative of phenol and is highly reactive to heat, flame, shock, or friction
    • Classified as a:
      • Flammable solid when wetted with more than 30% water
      • High explosive with less than 30% water (wetted product is considerably less shock sensitive than the dry acid)
    • Never allow picric acid to dry out — particularly on metal or concrete surfaces.
  • Health hazards:
    • Toxic by all routes of entry (i.e., inhalation, ingestion, dermal)
    • Produces toxic products on decomposition
    • Skin irritant and allergen
  • Reactivity:
    • Picric acid is highly reactive with a wide variety of materials (e.g., copper, zinc, lead, salts, plaster, concrete, ammonia, etc.) and extremely susceptible to the formation of picrate salts.
    • Picrate salts are formed by the reaction of picric acid with any of the following: metals, metal salts, bases, ammonia, and concrete.
    • Many of these salts are even more reactive and shock sensitive than the acid itself.
    • Metal picrates are particularly sensitive and can be formed with metals such as copper, nickel, lead, iron, and zinc.
    • Calcium picrate is formed by the reaction of picric acid with concrete.
  • Bottles of picric acid left on a laboratory shelf over a period of years are particularly dangerous for 2 reasons. Consider either of these situations extremely serious:
    1. The acid, which usually exists as a wetted paste, may dry out and cause the formation of shock-sensitive acid crystals.
    2. Introduction of impurities (e.g., via spatulas, degrading metal caps, etc.) into bottles that have been previously opened and are no longer airtight can cause formation of picrate salts inside the bottle or within the threads of the lid.
  • If possible, use a less dangerous product that can perform the same task.

Follow these training guidelines.

A PI or a knowledgeable designee must provide appropriate safety training.

  • Inform employees about handling picric acid, its specific hazards, and health effects.
  • Explain possible routes of exposure, as appropriate:
    • Skin absorption
    • Ingestion
    • Inhalation
  • Provide personal protective equipment and engineering controls, and train employees in their proper use.
  • Post emergency procedures in the lab and make sure everyone who works with picric acid is familiar with them.
  • Consult the chemical safety officer, (858) 822-1579, on training procedures for any new or revised projects involving large quantities of picric acid.
  • Keep training records on file, including:
    • Information covered
    • Date
    • Names
    • Employee signatures

Be prepared for accidental spills.

  • Print and keep the Material Safety Data Sheet for picric acid with your emergency supplies.
  • Know the location of safety equipment, including eyewash, shower station, first aid kit, and Emergency Guide.
  • Do not attempt to clean up spills! Picric acid spills are very serious and require immediate cleanup by Environment, Health & Safety (EH&S). Follow these instructions when a spill occurs:
    • Restrict access to the spill area and notify others.
    • Contact EH&S immediately:
      (858) 534-3660, Monday – Friday, 8 a.m. – 4:30 p.m.
      After hours, call Campus Police, (858) 534-4357.

Follow these purchasing and storage guidelines.

  • Buy the least amount of picric acid the work requires. Do not buy in large quantities to save money.
  • Label all containers with this information:
    • Name of the material
    • Concentration
    • Warnings
    • Date
    • Preparer's initials
  • Label the work area with a sign saying "Picric Acid Use Area."
  • Follow these storage guidelines:
    • Store unused liquid inventory in a polyethylene secondary container, large enough to capture the entire contents should the original container leak or rupture.
    • Store away from strong oxidizing agents, bases, most common metals, ammonia, and strong reducing agents.
    • Keep picric acid saturated. Never touch or move dry picric acid or picrate salts under any circumstances.
  • Control inventory storage time:
    • Flag picric acid on your laboratory inventory for annual review.
    • Do not store picric acid for more than 2 years.
    • Old picric acid is particularly dangerous. Follow these steps if old or previously unaccounted for containers of picric acid are discovered:
      • DO NOT TOUCH THE CONTAINER! Depending on the age of the bottle and condition of the product inside, even a minor disturbance could be dangerous. Crystals may have formed between the lid and the container. Any attempt to open the container could cause a serious explosion.
      • Contact EH&S immediately, (858) 534-3660.
      • Restrict access to the area.

Control the hazards.

  • Engineering controls:
  • Wear this personal protective equipment (PPE):
    • Lab coat with sleeves fully extended to the wrists
    • Safety glasses or splash goggles and face shield
    • Neoprene gloves
    • Full-length pants
    • Closed-toe shoes
    Follow these PPE guidelines:
    • Always double-check your PPE before each use of picric acid.
    • Never re-use disposal gloves.
    • Leave all personal protective equipment in the lab when your work is complete.
  • Restrict access to the work area.
  • Keep container sizes and quantities in the work area as small as possible.
  • Perform a dry run to work out any potential pitfalls.
  • If you suspect equipment has been contaminated with picric acid, contact an EH&S Research Assistance Program specialist.

Act quickly if an exposure occurs.

Give first aid treatment, then seek medical attention immediately for any and all picric acid exposures. Treat any exposure seriously, no matter how slight it may seem at the moment.

  • Ingestion: Seek medical attention immediately.
  • Skin exposure: Flush exposed skin with water for at least 15 minutes while removing any contaminated clothing.
  • Eye exposure: Flush eyes with water for at least 15 minutes. Affected individuals may need help holding their eyes open under water. Seek medical attention immediately at an emergency room.
  • For all exposures:
    • Seek medical attention immediately at an emergency room.
    • Call Campus Police at (858) 534-4357 (534-HELP) and request an ambulance if transportation is necessary.
    • Call Poison Control, (800) 222-1222, if additional information is needed.

Dispose of waste properly.

Read about how to:

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For more information, contact the chemical safety officer, (858) 822-1579.

Notice: Disposal of hazardous waste using sinks, intentional evaporation, or as regular trash is against the law. Campus laboratories must abide by strict state and federal waste disposal requirements. You may be held liable for violations of applicable laws.