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THE
ORCBS > Chemical
Safety
> Programs & Guidelines
>
SAFE USE OF
PERCHLORIC ACID
Perchloric acid
is a strong acid used for complete digestions of organic material.
It is normally supplied in bottles of up to one gallon in capacity
at 70-72% strength. In many respects, its hazards are similar to those
of nitric acid, as both are strong oxidants. Perchloric acid presents
an additional hazard in that perchloric acid mist and vapor can condense
in ventilation systems to form metallic perchlorates, which can be
explosive.
Researchers
using or anticipating using perchloric acid in their experiments
should keep the following in mind:
- Perchloric
acid digestions of any size must be performed only in a fume hood.
No open benchtop digestions should be performed.
- Any hood
which is used for perchloric acid digestions must be properly
constructed for use with perchloric acid.
- Perchloric
acid digestions require a special perchloric acid hood with a
washdown system, or if infrequent use of small quantities, a hood
fitted with a vapor trap apparatus similar to a micro Kjeldahl.
- Regardless
of the size of the digestion, no organic solvents should be in
the hood during the digestion. Solvents must never be stored
or used in a designated perchloric acid hood at any time. These
hoods should be posted with a label stating "Perchloric
Acid Use Only. Organic Chemical Prohibited".
- When diluting
perchloric acid (or any other acid) always add ACID TO WATER,
not the reverse.
- Perchloric
acid will attack researcher's tissues as easily as it will attack
sample tissue. To prevent injury, goggles or face shield, gloves,
and apron should be worn when handling perchloric acid.
- Because of
the potential for explosion, no work should be done on a hood
used for perchloric acid digestions until it has been thoroughly
decontaminated. Contact the ORCBS at 355-0153.
- Perchloric
acid waste must not be mixed with any other waste. It should be
put into acid-resistant bottles (preferably the original acid
container), clearly labeled, and treated as hazardous chemical
waste.
- Perchloric
acid should be stored segregated from all other chemicals and
inside secondary containment (such as a pyrex baking dish or plastic
dish pan). It must not be stored near organic acids such as acetic
acid, near bases, or near other organic or flammable material.
If you have
any questions about safe use and handling of perchloric acid, or
wish to have a fume hood approved for use with perchloric acid,
please contact the ORCBS at 355-0153.
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