Analytical Notes
Agilent Vapor Generation Accessory VGA 77 and VGA 77P User’s Guide 65
Dilute mercury solutions tend to be unstable; all analytical solutions
should be stabilized by the addition of nitric acid (5% v/v) and
hydrochloric acid (5% v/v). Prepare fresh standards daily.
If you are using the AA module:
Acceptable results can be obtained with the standard absorption cell,
however the flow-through mercury cell is recommended since this
will generally provide better analytical sensitivity and precision.
AA mercury determination is a cold vapor technique. Mercury is best
determined with a cold cell as the analytical sensitivity is reduced
when the cell is heated. Under no circumstances should the flow-
through cell be heated.
CAUTION
Heating the flow-through cell may damage it.
If you are experiencing problems with carryover of water vapor into
the cell (or condensation in the cell), heating of the flow cell can
eliminate this. One approach to heating the cell is to use the ETC 60
Electrothermal Temperature Controller programmed at 300 °C.
Alternately, another switch in heat source (like a lamp) can reduce
the occurrence of this problem.
For locations where the discharge of mercury vapor in nanogram
quantities is not permitted, the standard absorption cell is not
suitable and you should use the flow-through mercury cell together
with a suitable trap. Refer to Page 41.
Mercury can be determined using stannous chloride as the reductant.
Reductant container: SnCl
2
(25% w/v) in HCl (20% v/v)
Acid container: H
2
O
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