Definitions and Abbreviations
| HClO4 | (Perchloric Acid) |
| PPM | (parts per million, molecules of the compound per one million parts of air) |
| PEL | (Permissible Expose Limit) - Not Applicable. |
| SOP | (Standard Operating Procedure) |
| TLV | (Threshold Limit Value)- A derived number for the continual exposure (8 hrs) that should cause no irritation or toxic effect. There is no applicable TLV for Perchloric Acid. |
| IDLH | (Immediately Dangerous to Life and Health) |
| CFR | (Code of Federal Regulations) |
| EPA | (Environmental Protection Agency) |
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 complying with 40 CFR 160 and educating the Tufts community in the safe use of perchloric acid. All Tufts University staff, students and employees who work in labs containing Perchloric 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 perchloric acid.
Perchloric acid is a commonly used laboratory reagent. Most perchloric acid is sold in 60%-62% or 70%-72% acid in water. It is a clear, colorless liquid with no odor. The material is not a 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 heat¹. Organic materials are especially susceptible to spontaneous combustion due to contact with perchloric acid. Routes of exposure include inhalation and ingestion. Skin contact results in localized cracking and inflammation. Perchloric acid is not listed as a carcinogen.
Incompatables include flammables, acetic anhydride, bases, most metals and organic materials. As a result of its wide range of incompatible chemicals, perchloric acid is difficult to keep safely in storage. Ideally, perchloric 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 perchloric acid should always be performed in a chemical fume hood. Care should be taken to clear the hood of all organics, flammables, and other incompatables. Personal protective equipment including the appropriate gloves, safety glasses, and lab coat or apron must be worn.
Heating perchloric acid beyond room temperature results in HClO4 mist. This mist has been known to condense in the duct work of fume hoods and form explosive metallic perchlorates. Special perchloric acid fume hoods equipped with a wash down system or trap apparatus may be required in order to remove these explosive compounds. HClO4 can be boiled safely, but contact of the boiling acid or the hot vapor with organic matter, or even easily oxidized inorganic matter will lead to serious explosions². For this reason it is imperative that any work involving the application of heat to HClO4 be performed with the knowledge of the EH&S office.
Perchloric acid is not a combustible. It will however cause fires to burn more intensely. In case of a fire involving HClO4, activate the fire alarm before taking any extinguishing actions. If you determine through your own life experience that is not imprudent for you to extinguish the fire, extinguish the flames with an extinguisher. Do not attempt to extinguish a fire involving high hazard materials or a fire that is larger than desk size. Please refer to the Tufts University Laboratory, Chemical and Biological Materials Safety Manual (section 11.2, titled FIRE/FIRE RELATED EMERGENCIES ) for more detailed information on fire control measures.
Perchloric acid spills are serious and care should be taken to follow all chemical spill clean up procedures carefully. All personal protective equipment including the appropriate gloves, safety glasses, and lab coat or apron must be worn. 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 or higher concentrations 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. If perchloric acid is ingested, drink approximately 8 oz. of water and seek medical attention. Do not induce vomiting.
Waste perchloric acid should be placed in an approved waste container and labeled/stored according to procedure. Where applicable, segregate HClO4 from other waste streams and place the container in secondary containment. Contact the EH&S office for disposal once the container is full.
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.
² 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. 70-71.
