ABC of Safety in the Biological Sciences - Perchloric Acid

 

ABC of Safety in the Biological Sciences

 


 

PERCHLORIC ACID (HCl04)

SYNONYMS
None known.
GENERAL PRECAUTIONS
Use a fume hood.
Highly toxic through all routes of exposure.
Causes permanent eye damage.
Keep away from oxidising materials.
Keep away from hydroxyl compounds.
Keep away from organic material.
Wash hands thoroughly after handling.
HEALTH HAZARD DATA
This substance can form explosive perchlorate esters with many hydroxyl compounds. In the presence of combustible or reducing materials it is very unstable and can produce violent explosions. It is highly toxic via all routes into the body and a splash to the eye can cause permanent eye damage. It is a corrosive substance and can cause severe burns.
TREATMENTS
Skin ­ remove contaminated clothing and immediately wash the affected area with large amounts of water until all evidence of the chemical has been removed (approximately 15 minutes). Apply a magnesia/glycerol paste to the affected area and in severe cases seek immediate medical attention. A magnesia/glycerol paste should be in your first aid kit if perchloric acid is handled in your laboratory. It is available off the shelf in pharmacies.
Eyes ­ immediately wash the affected eye with large amounts of water until all evidence of the chemical has been removed (approximately 15 minutes). If pain or blurred vision persist seek medical attention.
Inhalation ­ remove from the area of exposure to fresh air. If breathing has ceased apply artificial respiration. Keep warm and allow to rest. If irritation persists or signs of toxicity develop seek medical attention.
Ingestion ­ wash out the mouth thoroughly with water and give water to drink followed by Milk of Magnesia. If signs of toxicity develop seek immediate medical attention. Milk of Magnesia should be part of your laboratory first aid kit if perchloric acid is handled in your laboratory. It is available off the shelf in pharmacies.
INCOMPATIBILITY
Heating produces toxic fumes of chlorine compounds.
Perchloric acid is incompatible with acetic anhydride or other dehydrating agents.
Nitric acid and cellulose material ­ explosive.
Hydroxyl compounds ­ explosive.
Dimethyl sulphoxide ­ explosive.
Ketones and glycols ­ violent reactions.
Ferrous sulphate ­ explosive.
Reducing agents ­ explosive.
STORAGE
Store in a cool, dry atmosphere away from heat and incompatible substances.
HANDLING
This is a highly toxic substance ­ use a fume hood to keep the level of exposure as low as possible. Wear protective clothing to avoid any sort of bodily contact. A long sleeved laboratory coat or gown, rubber gloves, safety goggles and a face mask as a minimum standard. The fume hood should be constructed of non­combustible materials.
DISPOSAL
WEAR:
Rubber gloves, face shield and laboratory coat. A body shield should be available for the more active agents. Replace the face shield with self contained breathing apparatus for such agents as chlorine and bromine.
SPILLS:
Gas leak: if the valve is leaking because it cannot be closed, the gas can be bubbled through a reducer (sodium sulphite) and excess sodium bicarbonate solution. Be sure to include a trap in the line to prevent the solution being sucked back into the cylinder. If this cannot be done the cylinder should be placed in or adjacent to a fume hood and left to bleed off. If the leak is in the valve assembly, a plastic bag can be fastened over the head of the cylinder which can then be taken outside or to a fume hood.
Liquid or solid: cover with a reducer (sodium thiosulphate, a bisulphite or a ferrous salt not carbon, sulphur or strong reducing agent). Mix well and spray with water. A sulphite or a ferrous salt will require addition of 3mol/l sulphuric acid to promote a rapid reduction. Scoop the slurry into a container of water and neutralise with soda ash. Discharge to sewer with a large excess of water. Wash the site thoroughly with a soap solution containing some reducer.
PACKAGE LOTS:
Add to a large volume of concentrated solution of reducer (sodium thiosulphate, a bisulphite or a ferrous salt and acidify with 3mol/l sulphuric acid). When the reduction is completed add soda ash or dilute hydrochloric acid to neutralise the solution. Discharge to sewer with a large excess of water.
ENVIRONMENT:

 


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