Automatic Operation - Agilent Technologies VGA 77 User Manual

Operation

Automatic Operation

Operation of the VGA 77 is not interlocked to the system. In the event of gas
CAUTION
supply failure, pumping faults, or if the reagent containers are emptied, the
program will not be automatically stopped and results from the program will not
be analytically valid.
For ICP systems. At the end of an automatic run, the VGA 77 pump continues to
CAUTION
run and gas continues to flow. To avoid waste liquid flooding the system, set the
'Pump rate at end of sequence' on the Preferences page in ICP Expert II or on
the Sequence page in ICP Expert to a rate that ensures the removal of all waste
liquid from the gas/liquid separator (typically 40–45 rpm).
Observe the following general rules, but refer to the appropriate
instrument operation or system manual for specific operating
instructions.
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The VGA 77 technique requires the use of acids at high
concentrations. You must therefore ensure that the sample probe
on the autosampler is corrosion-resistant. The Agilent SPS 3 is
fitted with a corrosion-resistant probe. This probe should always
be used for VGA 77 applications.
When connecting the autosampler to the VGA 77 uptake
capillary, ensure that the joint is leak-free and offers minimal
dead volume by keeping the connecting tube as short as possible.
The uptake from the autosampler to the vapor generator is the
only connection required between VGA 77 and other system
components—no electrical interconnection is required.
Remember to enter a suitable delay time to allow for the extra
time needed for the solution to emerge from the autosampler
tubing. Also check the stabilization times.
In the software, select the required number of replicate
measurements to be taken and select the appropriate re-
calibration and reslope frequencies.
Agilent Vapor Generation Accessory VGA 77 and VGA 77P User's Guide