Definitions and Abbreviations
| HNO3 | (Nitric Acid) |
| PPM | (parts per million, molecules of the compound per one million parts of air) |
| PEL | (Permissible Expose Limit) - 2 ppm |
| SOP | (Standard Operating Procedure) |
| TLV | (Threshold Limit Value) - A derived number for the continual exposure that should cause no irritation or toxic effect. The TLV for Nitric Acid is listed as 2 ppm. |
| IDLH | (Immediately Dangerous to Life and Health) - At levels greater than or equal to 25ppm HNO 3 is recognized as immediately dangerous to life and health. |
| CFR | (Code of Federal Regulations) |
| EPA | (Environmental Protection Agency) |
Procedure
Good Laboratory Practice standards put forth by the EPA in 40 CFR 160 mandate the implementation of standard operating procedures. This particular standard operating procedure was created by the Tufts Office of Environmental Health and Safety with the goal of compiling with 40 CFR 160 and educating the Tufts community in the proper use of Nitric Acid. All Tufts University staff, students and employees who work in labs containing Nitric Acid should familiarize themselves with this document. A sign off sheet should be kept that states the person has read this document and is aware of the unique dangers and special precautions that need to be taken when handling Nitric Acid.
Nitric Acid is a clear, colorless to slightly yellow inorganic acid. In concentrations above 70%, nitric acid is called "fuming" or "red fuming." The material is not combustible, however it is a strong oxidizer and care should be taken in storing it away from incompatibles (see below). Spontaneous ignition or combustion takes place when a substance reaches its ignition temperature without the application of external heat.¹ Materials susceptible to spontaneous combustion due to contact with Nitric Acid include oily rags, dust accumulations, and many organic materials. Routes of entry include inhalation and ingestion. Skin contact results in severe irritation and burns. Nitric Acid is not listed as a carcinogen.
Incompatibles include flammables, bases, hydrogen sulfide, organic materials, metals and metal compounds. As a result of its wide range of incompatable chemicals, Nitric acid is difficult to keep safely in storage. Ideally, nitric acid should be stored in its own acid cabinet. However due to space considerations this is not always possible. The next best place for storage is with other inorganic acids and within secondary containment. Work with Nitric acid should always be performed in a chemical fume hood. Care should be taken to clear the hood of organics, flammables, and other incompatables. Personal protective equipment including the appropriate gloves, safety glasses, and lab coat or apron must be worn.
Nitric acid spills are serious and care should be taken to follow all chemical spill clean up procedures carefully. Small or dilute concentrations (10 ml of >50% or 100 ml of dilute) can be cleaned up using a spill kit. The entire spill kit containing the clean up materials can then be labeled and placed in a satellite accumulation area for pickup and disposal. If large amounts of acid are spilled, or if the spill is beyond your ability and training to clean up, evacuate the laboratory and contact the Tufts Police from a safe location.
Symptoms of overexposure include irritation and/or burning of the affected area. Inhalation burns are serious and require immediate medical attention. Ingestion causes abdominal pain, vomiting, hemorrhaging, and organ perforation. If the acid is ingested, drink copious amounts of water and seek medical attention. Do not induce vomiting. If acid is spilled onto the body, wash the acid off with generous amounts of water for 15 min. Spills which occur over a large body surface require the use of the nearest safety shower and removal of contaminated clothing. The location of eye wash stations should be easily identified in case of eye contact. Flush eyes for a minimum of 5 minutes and notify the Tufts Police and the safety office immediately.
¹ Committee on Hazardous Substances in the Laboratory, Assembly of Mathematical and Physical Sciences, National Research Council. Prudent Practices for Handling Hazardous Chemicals in Laboratories.1981. pp. 59.
