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Safety Practices and Hazards
Do not use perchloric acid unless it is absolutely essential for sample preparation.
If perchloric acid must be used, it may be possible to reduce the risk of explosion
by taking the following measures:
NOTE
When solvent extractions of perchloric solutions are performed, some of the acid
may dissolve in the organic solvent that is subsequently aspirated. Also, if the
organic solution is aspirated while floating on the surface of the acid, do not allow
the capillary tube to drop below the organic layer and suck up aqueous perchloric
acid.
When using perchloric acid, wear approved ear protectors and approved safety
glasses and ensure that all instrument safety covers are in position.
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Use an air-acetylene flame instead of a nitrous oxide-acetylene flame.
Reduce the concentration of perchloric acid and metal in all analytical
solutions to the lowest practicable level. The concentration of perchloric acid
should be reduced in the digestion stage and further reduced by extending the
fuming stage.
Aspirate all solutions for the shortest practicable period.
Aspirate distilled water between samples. Minimize the aspiration of air.
Use separate spray chamber/liquid trap and drain assemblies for perchloric
acid analyses and organic solvent analyses to prevent perchloric acid from
mixing with organic solvent residues.
Never allow the burner to clog. Clean the burner frequently, washing it
thoroughly both inside and out.
Minimize the amount of acetone that is carried over with the acetylene by
taking the following precautions:
'Crack' the cylinder before use by gently opening the valve to check for any
drops or spray of acetone. Any cylinder showing acetone should be
returned to the supplier for replacement.
Store and use the cylinder in the vertical position.
Use only one instrument per cylinder.
Use only instrument grade acetylene.
Replace cylinders when the pressure drops to 700 kPa (100 psig).
Agilent 55B AA Spectrometer User's Guide
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