Agilent Technologies 7500 ICP-MS Operator's Manual page 93

Agilent 7500 ICP-MS ChemStation Operator's Manual
Tuning
8 In the Displayed Tuning Parameters tree display, select the check boxes of the
tuning parameters to be displayed in the ICP-MS Tuning - Doubly Charged Ion
window.
Parameters can be displayed or hidden by clicking on the [+]/[-] box.
Clicking on a parameter check box will alternately select or deselect the parameter.
A parameter in gray indicates that only some of the parameters contained within are
selected.
9 Click OK.
Clicking OK will close the Acquisition Parameters - Doubly Charged Ion window
and display the entered settings in the ICP-MS Tuning - Doubly Charged Ion
window.
10 Click Start to monitor the Agilent 7500 signals and view the numerical values in
the real-time display.
The window includes a box for a real-time display of the instrument's signal. The
box contains up to 200 data points. The current counts of each mass are given, and
the mean, RSD (relative standard deviation) of the signal, and the ratio of doubly
charged ion are given for the data points shown in the display.
11 If the ratio of the signal of the doubly charged ion to the element signal is equal
to or greater than 2.0% (3.5% in the case of Ba), then adjust the following
parameters to reduce the signal of the doubly charged ion.
RF Power, Smpl Depth, Carrier Gas, Makeup Gas, and PeriPump 1
Click each box and use the arrows to change the value.
The ratio of doubly charged ions mainly depends on the tuning conditions of the
sample introduction system. In order to reduce the ratio of doubly charged ions,
• Increase the Sampling depth
• Decrease the Carrier gas (or Makeup gas) flow
• Increase the RF Power
• Decrease the Sample flow rate
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